comparative study methodology

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Lau F, Kuziemsky C, editors. Handbook of eHealth Evaluation: An Evidence-based Approach [Internet]. Victoria (BC): University of Victoria; 2017 Feb 27.

Handbook of eHealth Evaluation: An Evidence-based Approach [Internet].

Chapter 10 methods for comparative studies.

Francis Lau and Anne Holbrook .

10.1. Introduction

In eHealth evaluation, comparative studies aim to find out whether group differences in eHealth system adoption make a difference in important outcomes. These groups may differ in their composition, the type of system in use, and the setting where they work over a given time duration. The comparisons are to determine whether significant differences exist for some predefined measures between these groups, while controlling for as many of the conditions as possible such as the composition, system, setting and duration.

According to the typology by Friedman and Wyatt (2006) , comparative studies take on an objective view where events such as the use and effect of an eHealth system can be defined, measured and compared through a set of variables to prove or disprove a hypothesis. For comparative studies, the design options are experimental versus observational and prospective versus retro­­spective. The quality of eHealth comparative studies depends on such aspects of methodological design as the choice of variables, sample size, sources of bias, confounders, and adherence to quality and reporting guidelines.

In this chapter we focus on experimental studies as one type of comparative study and their methodological considerations that have been reported in the eHealth literature. Also included are three case examples to show how these studies are done.

10.2. Types of Comparative Studies

Experimental studies are one type of comparative study where a sample of participants is identified and assigned to different conditions for a given time duration, then compared for differences. An example is a hospital with two care units where one is assigned a cpoe system to process medication orders electronically while the other continues its usual practice without a cpoe . The participants in the unit assigned to the cpoe are called the intervention group and those assigned to usual practice are the control group. The comparison can be performance or outcome focused, such as the ratio of correct orders processed or the occurrence of adverse drug events in the two groups during the given time period. Experimental studies can take on a randomized or non-randomized design. These are described below.

10.2.1. Randomized Experiments

In a randomized design, the participants are randomly assigned to two or more groups using a known randomization technique such as a random number table. The design is prospective in nature since the groups are assigned concurrently, after which the intervention is applied then measured and compared. Three types of experimental designs seen in eHealth evaluation are described below ( Friedman & Wyatt, 2006 ; Zwarenstein & Treweek, 2009 ).

Randomized controlled trials ( rct s) – In rct s participants are randomly assigned to an intervention or a control group. The randomization can occur at the patient, provider or organization level, which is known as the unit of allocation. For instance, at the patient level one can randomly assign half of the patients to receive emr reminders while the other half do not. At the provider level, one can assign half of the providers to receive the reminders while the other half continues with their usual practice. At the organization level, such as a multisite hospital, one can randomly assign emr reminders to some of the sites but not others. Cluster randomized controlled trials ( crct s) – In crct s, clusters of participants are randomized rather than by individual participant since they are found in naturally occurring groups such as living in the same communities. For instance, clinics in one city may be randomized as a cluster to receive emr reminders while clinics in another city continue their usual practice. Pragmatic trials – Unlike rct s that seek to find out if an intervention such as a cpoe system works under ideal conditions, pragmatic trials are designed to find out if the intervention works under usual conditions. The goal is to make the design and findings relevant to and practical for decision-makers to apply in usual settings. As such, pragmatic trials have few criteria for selecting study participants, flexibility in implementing the intervention, usual practice as the comparator, the same compliance and follow-up intensity as usual practice, and outcomes that are relevant to decision-makers.

10.2.2. Non-randomized Experiments

Non-randomized design is used when it is neither feasible nor ethical to randomize participants into groups for comparison. It is sometimes referred to as a quasi-experimental design. The design can involve the use of prospective or retrospective data from the same or different participants as the control group. Three types of non-randomized designs are described below ( Harris et al., 2006 ).

Intervention group only with pretest and post-test design – This design involves only one group where a pretest or baseline measure is taken as the control period, the intervention is implemented, and a post-test measure is taken as the intervention period for comparison. For example, one can compare the rates of medication errors before and after the implementation of a cpoe system in a hospital. To increase study quality, one can add a second pretest period to decrease the probability that the pretest and post-test difference is due to chance, such as an unusually low medication error rate in the first pretest period. Other ways to increase study quality include adding an unrelated outcome such as patient case-mix that should not be affected, removing the intervention to see if the difference remains, and removing then re-implementing the intervention to see if the differences vary accordingly. Intervention and control groups with post-test design – This design involves two groups where the intervention is implemented in one group and compared with a second group without the intervention, based on a post-test measure from both groups. For example, one can implement a cpoe system in one care unit as the intervention group with a second unit as the control group and compare the post-test medication error rates in both units over six months. To increase study quality, one can add one or more pretest periods to both groups, or implement the intervention to the control group at a later time to measure for similar but delayed effects. Interrupted time series ( its ) design – In its design, multiple measures are taken from one group in equal time intervals, interrupted by the implementation of the intervention. The multiple pretest and post-test measures decrease the probability that the differences detected are due to chance or unrelated effects. An example is to take six consecutive monthly medication error rates as the pretest measures, implement the cpoe system, then take another six consecutive monthly medication error rates as the post-test measures for comparison in error rate differences over 12 months. To increase study quality, one may add a concurrent control group for comparison to be more convinced that the intervention produced the change.

10.3. Methodological Considerations

The quality of comparative studies is dependent on their internal and external validity. Internal validity refers to the extent to which conclusions can be drawn correctly from the study setting, participants, intervention, measures, analysis and interpretations. External validity refers to the extent to which the conclusions can be generalized to other settings. The major factors that influence validity are described below.

10.3.1. Choice of Variables

Variables are specific measurable features that can influence validity. In comparative studies, the choice of dependent and independent variables and whether they are categorical and/or continuous in values can affect the type of questions, study design and analysis to be considered. These are described below ( Friedman & Wyatt, 2006 ).

Dependent variables – This refers to outcomes of interest; they are also known as outcome variables. An example is the rate of medication errors as an outcome in determining whether cpoe can improve patient safety. Independent variables – This refers to variables that can explain the measured values of the dependent variables. For instance, the characteristics of the setting, participants and intervention can influence the effects of cpoe . Categorical variables – This refers to variables with measured values in discrete categories or levels. Examples are the type of providers (e.g., nurses, physicians and pharmacists), the presence or absence of a disease, and pain scale (e.g., 0 to 10 in increments of 1). Categorical variables are analyzed using non-parametric methods such as chi-square and odds ratio. Continuous variables – This refers to variables that can take on infinite values within an interval limited only by the desired precision. Examples are blood pressure, heart rate and body temperature. Continuous variables are analyzed using parametric methods such as t -test, analysis of variance or multiple regression.

10.3.2. Sample Size

Sample size is the number of participants to include in a study. It can refer to patients, providers or organizations depending on how the unit of allocation is defined. There are four parts to calculating sample size. They are described below ( Noordzij et al., 2010 ).

Significance level – This refers to the probability that a positive finding is due to chance alone. It is usually set at 0.05, which means having a less than 5% chance of drawing a false positive conclusion. Power – This refers to the ability to detect the true effect based on a sample from the population. It is usually set at 0.8, which means having at least an 80% chance of drawing a correct conclusion. Effect size – This refers to the minimal clinically relevant difference that can be detected between comparison groups. For continuous variables, the effect is a numerical value such as a 10-kilogram weight difference between two groups. For categorical variables, it is a percentage such as a 10% difference in medication error rates. Variability – This refers to the population variance of the outcome of interest, which is often unknown and is estimated by way of standard deviation ( sd ) from pilot or previous studies for continuous outcome.

Sample Size Equations for Comparing Two Groups with Continuous and Categorical Outcome Variables.

An example of sample size calculation for an rct to examine the effect of cds on improving systolic blood pressure of hypertensive patients is provided in the Appendix. Refer to the Biomath website from Columbia University (n.d.) for a simple Web-based sample size / power calculator.

10.3.3. Sources of Bias

There are five common sources of biases in comparative studies. They are selection, performance, detection, attrition and reporting biases ( Higgins & Green, 2011 ). These biases, and the ways to minimize them, are described below ( Vervloet et al., 2012 ).

Selection or allocation bias – This refers to differences between the composition of comparison groups in terms of the response to the intervention. An example is having sicker or older patients in the control group than those in the intervention group when evaluating the effect of emr reminders. To reduce selection bias, one can apply randomization and concealment when assigning participants to groups and ensure their compositions are comparable at baseline. Performance bias – This refers to differences between groups in the care they received, aside from the intervention being evaluated. An example is the different ways by which reminders are triggered and used within and across groups such as electronic, paper and phone reminders for patients and providers. To reduce performance bias, one may standardize the intervention and blind participants from knowing whether an intervention was received and which intervention was received. Detection or measurement bias – This refers to differences between groups in how outcomes are determined. An example is where outcome assessors pay more attention to outcomes of patients known to be in the intervention group. To reduce detection bias, one may blind assessors from participants when measuring outcomes and ensure the same timing for assessment across groups. Attrition bias – This refers to differences between groups in ways that participants are withdrawn from the study. An example is the low rate of participant response in the intervention group despite having received reminders for follow-up care. To reduce attrition bias, one needs to acknowledge the dropout rate and analyze data according to an intent-to-treat principle (i.e., include data from those who dropped out in the analysis). Reporting bias – This refers to differences between reported and unreported findings. Examples include biases in publication, time lag, citation, language and outcome reporting depending on the nature and direction of the results. To reduce reporting bias, one may make the study protocol available with all pre-specified outcomes and report all expected outcomes in published results.

10.3.4. Confounders

Confounders are factors other than the intervention of interest that can distort the effect because they are associated with both the intervention and the outcome. For instance, in a study to demonstrate whether the adoption of a medication order entry system led to lower medication costs, there can be a number of potential confounders that can affect the outcome. These may include severity of illness of the patients, provider knowledge and experience with the system, and hospital policy on prescribing medications ( Harris et al., 2006 ). Another example is the evaluation of the effect of an antibiotic reminder system on the rate of post-operative deep venous thromboses ( dvt s). The confounders can be general improvements in clinical practice during the study such as prescribing patterns and post-operative care that are not related to the reminders ( Friedman & Wyatt, 2006 ).

To control for confounding effects, one may consider the use of matching, stratification and modelling. Matching involves the selection of similar groups with respect to their composition and behaviours. Stratification involves the division of participants into subgroups by selected variables, such as comorbidity index to control for severity of illness. Modelling involves the use of statistical techniques such as multiple regression to adjust for the effects of specific variables such as age, sex and/or severity of illness ( Higgins & Green, 2011 ).

10.3.5. Guidelines on Quality and Reporting

There are guidelines on the quality and reporting of comparative studies. The grade (Grading of Recommendations Assessment, Development and Evaluation) guidelines provide explicit criteria for rating the quality of studies in randomized trials and observational studies ( Guyatt et al., 2011 ). The extended consort (Consolidated Standards of Reporting Trials) Statements for non-pharmacologic trials ( Boutron, Moher, Altman, Schulz, & Ravaud, 2008 ), pragmatic trials ( Zwarestein et al., 2008 ), and eHealth interventions ( Baker et al., 2010 ) provide reporting guidelines for randomized trials.

The grade guidelines offer a system of rating quality of evidence in systematic reviews and guidelines. In this approach, to support estimates of intervention effects rct s start as high-quality evidence and observational studies as low-quality evidence. For each outcome in a study, five factors may rate down the quality of evidence. The final quality of evidence for each outcome would fall into one of high, moderate, low, and very low quality. These factors are listed below (for more details on the rating system, refer to Guyatt et al., 2011 ).

Design limitations – For rct s they cover the lack of allocation concealment, lack of blinding, large loss to follow-up, trial stopped early or selective outcome reporting. Inconsistency of results – Variations in outcomes due to unexplained heterogeneity. An example is the unexpected variation of effects across subgroups of patients by severity of illness in the use of preventive care reminders. Indirectness of evidence – Reliance on indirect comparisons due to restrictions in study populations, intervention, comparator or outcomes. An example is the 30-day readmission rate as a surrogate outcome for quality of computer-supported emergency care in hospitals. Imprecision of results – Studies with small sample size and few events typically would have wide confidence intervals and are considered of low quality. Publication bias – The selective reporting of results at the individual study level is already covered under design limitations, but is included here for completeness as it is relevant when rating quality of evidence across studies in systematic reviews.

The original consort Statement has 22 checklist items for reporting rct s. For non-pharmacologic trials extensions have been made to 11 items. For pragmatic trials extensions have been made to eight items. These items are listed below. For further details, readers can refer to Boutron and colleagues (2008) and the consort website ( consort , n.d.).

Title and abstract – one item on the means of randomization used. Introduction – one item on background, rationale, and problem addressed by the intervention. Methods – 10 items on participants, interventions, objectives, outcomes, sample size, randomization (sequence generation, allocation concealment, implementation), blinding (masking), and statistical methods. Results – seven items on participant flow, recruitment, baseline data, numbers analyzed, outcomes and estimation, ancillary analyses, adverse events. Discussion – three items on interpretation, generalizability, overall evidence.

The consort Statement for eHealth interventions describes the relevance of the consort recommendations to the design and reporting of eHealth studies with an emphasis on Internet-based interventions for direct use by patients, such as online health information resources, decision aides and phr s. Of particular importance is the need to clearly define the intervention components, their role in the overall care process, target population, implementation process, primary and secondary outcomes, denominators for outcome analyses, and real world potential (for details refer to Baker et al., 2010 ).

10.4. Case Examples

10.4.1. pragmatic rct in vascular risk decision support.

Holbrook and colleagues (2011) conducted a pragmatic rct to examine the effects of a cds intervention on vascular care and outcomes for older adults. The study is summarized below.

Setting – Community-based primary care practices with emr s in one Canadian province. Participants – English-speaking patients 55 years of age or older with diagnosed vascular disease, no cognitive impairment and not living in a nursing home, who had a provider visit in the past 12 months. Intervention – A Web-based individualized vascular tracking and advice cds system for eight top vascular risk factors and two diabetic risk factors, for use by both providers and patients and their families. Providers and staff could update the patient’s profile at any time and the cds algorithm ran nightly to update recommendations and colour highlighting used in the tracker interface. Intervention patients had Web access to the tracker, a print version mailed to them prior to the visit, and telephone support on advice. Design – Pragmatic, one-year, two-arm, multicentre rct , with randomization upon patient consent by phone, using an allocation-concealed online program. Randomization was by patient with stratification by provider using a block size of six. Trained reviewers examined emr data and conducted patient telephone interviews to collect risk factors, vascular history, and vascular events. Providers completed questionnaires on the intervention at study end. Patients had final 12-month lab checks on urine albumin, low-density lipoprotein cholesterol, and A1c levels. Outcomes – Primary outcome was based on change in process composite score ( pcs ) computed as the sum of frequency-weighted process score for each of the eight main risk factors with a maximum score of 27. The process was considered met if a risk factor had been checked. pcs was measured at baseline and study end with the difference as the individual primary outcome scores. The main secondary outcome was a clinical composite score ( ccs ) based on the same eight risk factors compared in two ways: a comparison of the mean number of clinical variables on target and the percentage of patients with improvement between the two groups. Other secondary outcomes were actual vascular event rates, individual pcs and ccs components, ratings of usability, continuity of care, patient ability to manage vascular risk, and quality of life using the EuroQol five dimensions questionnaire ( eq-5D) . Analysis – 1,100 patients were needed to achieve 90% power in detecting a one-point pcs difference between groups with a standard deviation of five points, two-tailed t -test for mean difference at 5% significance level, and a withdrawal rate of 10%. The pcs , ccs and eq-5D scores were analyzed using a generalized estimating equation accounting for clustering within providers. Descriptive statistics and χ2 tests or exact tests were done with other outcomes. Findings – 1,102 patients and 49 providers enrolled in the study. The intervention group with 545 patients had significant pcs improvement with a difference of 4.70 ( p < .001) on a 27-point scale. The intervention group also had significantly higher odds of rating improvements in their continuity of care (4.178, p < .001) and ability to improve their vascular health (3.07, p < .001). There was no significant change in vascular events, clinical variables and quality of life. Overall the cds intervention led to reduced vascular risks but not to improved clinical outcomes in a one-year follow-up.

10.4.2. Non-randomized Experiment in Antibiotic Prescribing in Primary Care

Mainous, Lambourne, and Nietert (2013) conducted a prospective non-randomized trial to examine the impact of a cds system on antibiotic prescribing for acute respiratory infections ( ari s) in primary care. The study is summarized below.

Setting – A primary care research network in the United States whose members use a common emr and pool data quarterly for quality improvement and research studies. Participants – An intervention group with nine practices across nine states, and a control group with 61 practices. Intervention – Point-of-care cds tool as customizable progress note templates based on existing emr features. cds recommendations reflect Centre for Disease Control and Prevention ( cdc ) guidelines based on a patient’s predominant presenting symptoms and age. cds was used to assist in ari diagnosis, prompt antibiotic use, record diagnosis and treatment decisions, and access printable patient and provider education resources from the cdc . Design – The intervention group received a multi-method intervention to facilitate provider cds adoption that included quarterly audit and feedback, best practice dissemination meetings, academic detailing site visits, performance review and cds training. The control group did not receive information on the intervention, the cds or education. Baseline data collection was for three months with follow-up of 15 months after cds implementation. Outcomes – The outcomes were frequency of inappropriate prescribing during an ari episode, broad-spectrum antibiotic use and diagnostic shift. Inappropriate prescribing was computed by dividing the number of ari episodes with diagnoses in the inappropriate category that had an antibiotic prescription by the total number of ari episodes with diagnosis for which antibiotics are inappropriate. Broad-spectrum antibiotic use was computed by all ari episodes with a broad-spectrum antibiotic prescription by the total number of ari episodes with an antibiotic prescription. Antibiotic drift was computed in two ways: dividing the number of ari episodes with diagnoses where antibiotics are appropriate by the total number of ari episodes with an antibiotic prescription; and dividing the number of ari episodes where antibiotics were inappropriate by the total number of ari episodes. Process measure included frequency of cds template use and whether the outcome measures differed by cds usage. Analysis – Outcomes were measured quarterly for each practice, weighted by the number of ari episodes during the quarter to assign greater weight to practices with greater numbers of relevant episodes and to periods with greater numbers of relevant episodes. Weighted means and 95% ci s were computed separately for adult and pediatric (less than 18 years of age) patients for each time period for both groups. Baseline means in outcome measures were compared between the two groups using weighted independent-sample t -tests. Linear mixed models were used to compare changes over the 18-month period. The models included time, intervention status, and were adjusted for practice characteristics such as specialty, size, region and baseline ari s. Random practice effects were included to account for clustering of repeated measures on practices over time. P -values of less than 0.05 were considered significant. Findings – For adult patients, inappropriate prescribing in ari episodes declined more among the intervention group (-0.6%) than the control group (4.2%)( p = 0.03), and prescribing of broad-spectrum antibiotics declined by 16.6% in the intervention group versus an increase of 1.1% in the control group ( p < 0.0001). For pediatric patients, there was a similar decline of 19.7% in the intervention group versus an increase of 0.9% in the control group ( p < 0.0001). In summary, the cds had a modest effect in reducing inappropriate prescribing for adults, but had a substantial effect in reducing the prescribing of broad-spectrum antibiotics in adult and pediatric patients.

10.4.3. Interrupted Time Series on EHR Impact in Nursing Care

Dowding, Turley, and Garrido (2012) conducted a prospective its study to examine the impact of ehr implementation on nursing care processes and outcomes. The study is summarized below.

Setting – Kaiser Permanente ( kp ) as a large not-for-profit integrated healthcare organization in the United States. Participants – 29 kp hospitals in the northern and southern regions of California. Intervention – An integrated ehr system implemented at all hospitals with cpoe , nursing documentation and risk assessment tools. The nursing component for risk assessment documentation of pressure ulcers and falls was consistent across hospitals and developed by clinical nurses and informaticists by consensus. Design – its design with monthly data on pressure ulcers and quarterly data on fall rates and risk collected over seven years between 2003 and 2009. All data were collected at the unit level for each hospital. Outcomes – Process measures were the proportion of patients with a fall risk assessment done and the proportion with a hospital-acquired pressure ulcer ( hapu ) risk assessment done within 24 hours of admission. Outcome measures were fall and hapu rates as part of the unit-level nursing care process and nursing sensitive outcome data collected routinely for all California hospitals. Fall rate was defined as the number of unplanned descents to the floor per 1,000 patient days, and hapu rate was the percentage of patients with stages i-IV or unstageable ulcer on the day of data collection. Analysis – Fall and hapu risk data were synchronized using the month in which the ehr was implemented at each hospital as time zero and aggregated across hospitals for each time period. Multivariate regression analysis was used to examine the effect of time, region and ehr . Findings – The ehr was associated with significant increase in document rates for hapu risk (2.21; 95% CI 0.67 to 3.75) and non-significant increase for fall risk (0.36; -3.58 to 4.30). The ehr was associated with 13% decrease in hapu rates (-0.76; -1.37 to -0.16) but no change in fall rates (-0.091; -0.29 to 011). Hospital region was a significant predictor of variation for hapu (0.72; 0.30 to 1.14) and fall rates (0.57; 0.41 to 0.72). During the study period, hapu rates decreased significantly (-0.16; -0.20 to -0.13) but not fall rates (0.0052; -0.01 to 0.02). In summary, ehr implementation was associated with a reduction in the number of hapu s but not patient falls, and changes over time and hospital region also affected outcomes.

10.5. Summary

In this chapter we introduced randomized and non-randomized experimental designs as two types of comparative studies used in eHealth evaluation. Randomization is the highest quality design as it reduces bias, but it is not always feasible. The methodological issues addressed include choice of variables, sample size, sources of biases, confounders, and adherence to reporting guidelines. Three case examples were included to show how eHealth comparative studies are done.

• Baker T. B., Gustafson D. H., Shaw B., Hawkins R., Pingree S., Roberts L., Strecher V. Relevance of consort reporting criteria for research on eHealth interventions. Patient Education and Counselling. 2010; 81 (suppl. 7):77–86. [ PMC free article : PMC2993846 ] [ PubMed : 20843621 ]
• Columbia University. (n.d.). Statistics: sample size / power calculation. Biomath (Division of Biomathematics/Biostatistics), Department of Pediatrics. New York: Columbia University Medical Centre. Retrieved from http://www ​.biomath.info/power/index.htm .
• Boutron I., Moher D., Altman D. G., Schulz K. F., Ravaud P. consort Group. Extending the consort statement to randomized trials of nonpharmacologic treatment: Explanation and elaboration. Annals of Internal Medicine. 2008; 148 (4):295–309. [ PubMed : 18283207 ]
• Cochrane Collaboration. Cochrane handbook. London: Author; (n.d.) Retrieved from http://handbook ​.cochrane.org/
• consort Group. (n.d.). The consort statement . Retrieved from http://www ​.consort-statement.org/
• Dowding D. W., Turley M., Garrido T. The impact of an electronic health record on nurse sensitive patient outcomes: an interrupted time series analysis. Journal of the American Medical Informatics Association. 2012; 19 (4):615–620. [ PMC free article : PMC3384108 ] [ PubMed : 22174327 ]
• Friedman C. P., Wyatt J.C. Evaluation methods in biomedical informatics. 2nd ed. New York: Springer Science + Business Media, Inc; 2006.
• Guyatt G., Oxman A. D., Akl E. A., Kunz R., Vist G., Brozek J. et al. Schunemann H. J. grade guidelines: 1. Introduction – grade evidence profiles and summary of findings tables. Journal of Clinical Epidemiology. 2011; 64 (4):383–394. [ PubMed : 21195583 ]
• Harris A. D., McGregor J. C., Perencevich E. N., Furuno J. P., Zhu J., Peterson D. E., Finkelstein J. The use and interpretation of quasi-experimental studies in medical informatics. Journal of the American Medical Informatics Association. 2006; 13 (1):16–23. [ PMC free article : PMC1380192 ] [ PubMed : 16221933 ]
• The Cochrane Collaboration. Cochrane handbook for systematic reviews of interventions. Higgins J. P. T., Green S., editors. London: 2011. (Version 5.1.0, updated March 2011) Retrieved from http://handbook ​.cochrane.org/
• Holbrook A., Pullenayegum E., Thabane L., Troyan S., Foster G., Keshavjee K. et al. Curnew G. Shared electronic vascular risk decision support in primary care. Computerization of medical practices for the enhancement of therapeutic effectiveness (compete III) randomized trial. Archives of Internal Medicine. 2011; 171 (19):1736–1744. [ PubMed : 22025430 ]
• Mainous III A. G., Lambourne C. A., Nietert P.J. Impact of a clinical decision support system on antibiotic prescribing for acute respiratory infections in primary care: quasi-experimental trial. Journal of the American Medical Informatics Association. 2013; 20 (2):317–324. [ PMC free article : PMC3638170 ] [ PubMed : 22759620 ]
• Noordzij M., Tripepi G., Dekker F. W., Zoccali C., Tanck M. W., Jager K.J. Sample size calculations: basic principles and common pitfalls. Nephrology Dialysis Transplantation. 2010; 25 (5):1388–1393. Retrieved from http://ndt ​.oxfordjournals ​.org/content/early/2010/01/12/ndt ​.gfp732.short . [ PubMed : 20067907 ]
• Vervloet M., Linn A. J., van Weert J. C. M., de Bakker D. H., Bouvy M. L., van Dijk L. The effectiveness of interventions using electronic reminders to improve adherence to chronic medication: A systematic review of the literature. Journal of the American Medical Informatics Association. 2012; 19 (5):696–704. [ PMC free article : PMC3422829 ] [ PubMed : 22534082 ]
• Zwarenstein M., Treweek S., Gagnier J. J., Altman D. G., Tunis S., Haynes B., Oxman A. D., Moher D. for the consort and Pragmatic Trials in Healthcare (Practihc) groups. Improving the reporting of pragmatic trials: an extension of the consort statement. British Medical Journal. 2008; 337 :a2390. [ PMC free article : PMC3266844 ] [ PubMed : 19001484 ] [ CrossRef ]
• Zwarenstein M., Treweek S. What kind of randomized trials do we need? Canadian Medical Association Journal. 2009; 180 (10):998–1000. [ PMC free article : PMC2679816 ] [ PubMed : 19372438 ]

Appendix. Example of Sample Size Calculation

This is an example of sample size calculation for an rct that examines the effect of a cds system on reducing systolic blood pressure in hypertensive patients. The case is adapted from the example described in the publication by Noordzij et al. (2010) .

(a) Systolic blood pressure as a continuous outcome measured in mmHg

Based on similar studies in the literature with similar patients, the systolic blood pressure values from the comparison groups are expected to be normally distributed with a standard deviation of 20 mmHg. The evaluator wishes to detect a clinically relevant difference of 15 mmHg in systolic blood pressure as an outcome between the intervention group with cds and the control group without cds . Assuming a significance level or alpha of 0.05 for 2-tailed t -test and power of 0.80, the corresponding multipliers 1 are 1.96 and 0.842, respectively. Using the sample size equation for continuous outcome below we can calculate the sample size needed for the above study.

n = 2[(a+b)2σ2]/(μ1-μ2)2 where

n = sample size for each group

μ1 = population mean of systolic blood pressures in intervention group

μ2 = population mean of systolic blood pressures in control group

μ1- μ2 = desired difference in mean systolic blood pressures between groups

σ = population variance

a = multiplier for significance level (or alpha)

b = multiplier for power (or 1-beta)

Providing the values in the equation would give the sample size (n) of 28 samples per group as the result

n = 2[(1.96+0.842)2(202)]/152 or 28 samples per group

(b) Systolic blood pressure as a categorical outcome measured as below or above 140 mmHg (i.e., hypertension yes/no)

In this example a systolic blood pressure from a sample that is above 140 mmHg is considered an event of the patient with hypertension. Based on published literature the proportion of patients in the general population with hypertension is 30%. The evaluator wishes to detect a clinically relevant difference of 10% in systolic blood pressure as an outcome between the intervention group with cds and the control group without cds . This means the expected proportion of patients with hypertension is 20% (p1 = 0.2) in the intervention group and 30% (p2 = 0.3) in the control group. Assuming a significance level or alpha of 0.05 for 2-tailed t -test and power of 0.80 the corresponding multipliers are 1.96 and 0.842, respectively. Using the sample size equation for categorical outcome below, we can calculate the sample size needed for the above study.

n = [(a+b)2(p1q1+p2q2)]/χ2

p1 = proportion of patients with hypertension in intervention group

q1 = proportion of patients without hypertension in intervention group (or 1-p1)

p2 = proportion of patients with hypertension in control group

q2 = proportion of patients without hypertension in control group (or 1-p2)

χ = desired difference in proportion of hypertensive patients between two groups

Providing the values in the equation would give the sample size (n) of 291 samples per group as the result

n = [(1.96+0.842)2((0.2)(0.8)+(0.3)(0.7))]/(0.1)2 or 291 samples per group

From Table 3 on p. 1392 of Noordzij et al. (2010).

This publication is licensed under a Creative Commons License, Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0): see https://creativecommons.org/licenses/by-nc/4.0/

• Cite this Page Lau F, Holbrook A. Chapter 10 Methods for Comparative Studies. In: Lau F, Kuziemsky C, editors. Handbook of eHealth Evaluation: An Evidence-based Approach [Internet]. Victoria (BC): University of Victoria; 2017 Feb 27.
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3. Comparative Research Methods

This chapter examines the ‘art of comparing’ by showing how to relate a theoretically guided research question to a properly founded research answer by developing an adequate research design. It first considers the role of variables in comparative research, before discussing the meaning of ‘cases’ and case selection. It then looks at the ‘core’ of the comparative research method: the use of the logic of comparative inquiry to analyse the relationships between variables (representing theory), and the information contained in the cases (the data). Two logics are distinguished: Method of Difference and Method of Agreement. The chapter concludes with an assessment of some problems common to the use of comparative methods.

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3. Comparative research methods

This chapter examines the ‘art of comparing’ by showing how to relate a theoretically guided research question to a properly founded research answer by developing an adequate research design. It first considers the role of variables in comparative research before discussing the meaning of ‘cases’ and case selection. It then looks at the ‘core’ of the comparative research method: the use of the logic of comparative inquiry to analyse the relationships between variables (representing theory) and the information contained in the cases (the data). Two logics are distinguished: Method of Difference and Method of Agreement. The chapter concludes with an assessment of some problems common to the use of comparative methods.

Rethinking Comparison

Qualitative comparative methods – and specifically controlled qualitative comparisons – are central to the study of politics. They are not the only kind of comparison, though, that can help us better understand political processes and outcomes. Yet there are few guides for how to conduct non-controlled comparative research. This volume brings together chapters from more than a dozen leading methods scholars from across the discipline of political science, including positivist and interpretivist scholars, qualitative methodologists, mixed-methods researchers, ethnographers, historians, and statisticians. Their work revolutionizes qualitative research design by diversifying the repertoire of comparative methods available to students of politics, offering readers clear suggestions for what kinds of comparisons might be possible, why they are useful, and how to execute them. By systematically thinking through how we engage in qualitative comparisons and the kinds of insights those comparisons produce, these collected essays create new possibilities to advance what we know about politics.

PERAN PEMUDA RELAWAN DEMOKRASI DALAM MENINGKATKAN PARTISIPASI POLITIK MASYARAKAT PADA PEMILIHAN UMUM LEGISLATIF TAHUN 2014 DAN IMPLIKASINYA TERHADAP KETAHANAN POLITIK WILAYAH (STUDI PADA RELAWAN DEMOKRASI BANYUMAS, JAWA TENGAH)

This research was going to described the role of Banyumas Democracy Volunteer ( Relawan Demokrasi Banyumas) in increasing political public partitipation in Banyumas’s legislative election 2014 and its implication to Banyumas’s political resilience. This research used qualitative research design as a research method. Data were collected by in depth review, observation and documentation. This research used purpossive sampling technique with stakeholder sampling variant to pick informants. The research showed that Banyumas Democracy Volunteer had a positive role in developing political resilience in Banyumas. Their role was gave political education and election education to voters in Banyumas. In the other words, Banyumas Democracy Volunteer had a vital role in developing ideal political resilience in Banyumas.Keywords: Banyumas Democracy Volunteer, Democracy, Election, Political Resilience of Region.

Ezer Kenegdo: Eksistensi Perempuan dan Perannya dalam Keluarga

AbstractPurpose of this study was to describe the meaning of ezer kenegdo and to know position and role of women in the family. The research method used is qualitative research methods (library research). The term of “ ezer kenegdo” refer to a helper but her position withoutsuperiority and inferiority. “The patner model” between men and women is uderstood in relation to one another as the same function, where differences are complementary and mutually beneficial in all walks of life and human endeavors.Keywords: Ezer Kenegdo; Women; Family.AbstrakTujuan penulisan artikel ini adalah untuk mendeskripsikan pengertian ezer kenegdo dan mengetahui kedudukan dan peran perempuan dalam keluarga. Metode yang digunakan adalah metode kualitatif library research. Ungkapan “ezer kenegdo” menunjuk pada seorang penolong namun kedudukannya adalah setara tanpa ada superioritas dan inferioritas. “Model kepatneran” antara laki-laki dan perempuan dipahami dengan hubungan satu dengan yang lain sebagai fungsi yang sama, yang mana perbedaan adalah saling melengkapi dan saling menguntungkan dalam semua lapisan kehidupan dan usaha manusia.Kata Kunci: Ezer Kenegdo, Prerempuan, Keluarga.

Commentary on ‘Opportunities and Challenges of Engaged Indigenous Scholarship’ (Van de Ven, Meyer, & Jing, 2018)

The mission ofManagement and Organization Review, founded in 2005, is to publish research about Chinese management and organizations, foreign organizations operating in China, or Chinese firms operating globally. The aspiration is to develop knowledge that is unique to China as well as universal knowledge that may transcend China. Articulated in the first editorial published in the inaugural issue of MOR (2005) and further elaborated in a second editorial (Tsui, 2006), the question of contextualization is framed, discussing the role of context in the choices of the research question, theory, measurement, and research design. The idea of ‘engaged indigenous research’ by Van de Ven, Meyer, and Jing (2018) describes the highest level of contextualization, with the local context serving as the primary factor guiding all the decisions of a research project. Tsui (2007: 1353) refers to it as ‘deep contextualization’.

PERAN DINAS KESEHATAN DALAM MENANGGULANGI GIZI BURUK ANAK DI KECAMATAN NGAMPRAH KABUPATEN BANDUNG BARAT

The title of this research is "The Role of the Health Office in Tackling Child Malnutrition in Ngamprah District, West Bandung Regency". The problem in this research is not yet optimal implementation of the Health Office in Overcoming Malnutrition in Children in Ngamprah District, West Bandung Regency. The research method that researchers use is descriptive research methods with a qualitative approach. The technique of determining the informants used was purposive sampling technique. The results showed that in carrying out its duties and functions, the health office, the Health Office had implemented a sufficiently optimal role seen from the six indicators of success in overcoming malnutrition, namely: All Posyandu carry out weighing operations at least once a month All toddlers are weighed, All cases of malnutrition are referred to the Puskemas Nursing or Home Sick, all cases of malnutrition are treated at the health center. Nursing or hospitalization is handled according to the management of malnutrition. All post-treatment malnourished toddlers receive assistance.

Jazz jem sessions in the aspect of listener perception

The purpose of the article is to identify the characteristic features ofjazz jam sessions as creative and concert events. The research methods arebased on the use of a number of empirical approaches. The historicalmethod has characterized the periodization of the emergence andpopularity of jam session as an artistic phenomenon. The use of themethod of comparison of jazz jam sessions and jazz concert made itpossible to determine the characteristic features of jams. An appeal toaxiological research methods has identified the most strikingimprovisational solos of leading jazz artists. Of particular importance inthe context of the article are the methods of analysis and synthesis,observation and generalization. It is important to pay attention to the use ofa structural-functional scientific-research method that indicates theeffectiveness of technological and execution processes on jams. Scientificinnovation. The article is about discovering the peculiarities of the jamsession phenomenon and defining the role of interaction between theaudience of improviser listeners and musicians throughout the jams. Theprocesses of development of jazz concerts and improvisations at jamsessions are revealed. Conclusions. The scientific research providedconfirms the fact that system of interactions between musicians amongthemselves and the audience, as well as improvisation of the performers atthe jam sessions is immense and infinite. That is why modern jazz singersand the audience will always strive for its development and understanding.This way is worth starting with repeated listening to improvisation, in theimmediate presence of the jam sessions (both participant and listener).

THE ROLE OF TECHNOLOGY INFORMATION SYSTEMS AND APPLICATION OF SAK ETAP ON DEVELOPMENT MODEL FINANCIAL POSITION REPORT

Bina Siswa SMA Plus Cisarua addressing in Jl. colonel canal masturi no. 64. At the time of document making, record-keeping of transaction relating to account real or financial position report account especially, Bina Siswa SMA Plus Cisarua has applied computer that is by using the application of Microsoft Office Word 2007 and Microsoft Excel 2007, in practice of control to relative financial position report account unable to be added with the duration process performed within financial statement making. For the problems then writer takes title: “The Role Of Technology Information Systems And Aplication Of SAK ETAP On Development Model Financial Position Report”. Research type which writer applies is research type academy, data type which writer applies is qualitative data and quantitative data, research design type which writer applies is research design deskriptif-analistis, research method which writer applies is descriptive research method, survey and eksperiment,  data collecting technique which writer applies is field researcher what consisted of interview and observation  library research, system development method which writer applies is methodologies orienting at process, data and output. System development structure applied is Iterasi. Design of information system applied is context diagram, data flow diagram, and flowchart. Design of this financial position report accounting information system according to statement of financial accounting standard SAK ETAP and output  consisted of information of accumulated fixed assets, receivable list, transaction summary of cash, transaction summary of bank and financial position report.

Dilema Hakim Pengadilan Agama dalam Menyelesaikan Perkara Hukum Keluarga Melalui Mediasi

This article aims to determine the role of judges in resolving family law cases through mediation in the Religious Courts, where judges have the position as state officials as regulated in Law Number 43 of 1999 concerning Basic Personnel, can also be a mediator in the judiciary. as regulated in Supreme Court Regulation Number 1 of 2016 concerning Mediation Procedures where judges have the responsibility to seek peace at every level of the trial and are also involved in mediation procedures. The research method used in this article uses normative legal research methods. Whereas until now judges still have a very important role in resolving family law cases in the Religious Courts due to the fact that there are still many negotiating processes with mediation assisted by judges, even though on the one hand the number of non-judge mediators is available, although in each region it is not evenly distributed in terms of number and capacity. non-judge mediator.

Anime affection on human IQ and behavior in Saudi Arabia

The present study attempted to determine the effects of watching anime and understanding if watching anime could affect the mental and social aspects of kids or other group of ages, and also to decide that the teenagers and children should watch anime or not. The research design used in this study is the descriptive research method and observational where in data and facts from direct observations and online questionnaires were used to answer the research question. The finding of this study suggested that anime viewers has higher level of general knowledge comparing with the non- anime viewers and as well as higher IQ level significantly in a specific group, besides anime can be used to spread a background about any culture and plays a role in increase the economy.

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Comparative Research Designs and Methods

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Instructor: Dirk Berg Schlosser

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• Research Methods
• Qualitative Comparative Analysis (QCA)
• comparative research
• Macro-quantitative methods

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There are 5 modules in this course

Emile Durkheim, one of the founders of modern empirical social science, once stated that the comparative method is the only one that suits the social sciences. But Descartes already had reminded us that “comparaison n’est pas raison”, which means that comparison is not reason (or theory) by itself.

This course provides an introduction and overview of systematic comparative analyses in the social sciences and shows how to employ this method for constructive explanation and theory building. It begins with comparisons of very few cases and specific “most similar” and “most different” research designs. A major part is then devoted to the often occurring situation of dealing with a small number of highly complex cases, for example when comparing EU member states. Latin American political systems, or particular policy areas. In response to this complexity, new approaches and software have been developed in recent years (“Qualitative Comparative Analysis”, QCA, and related methods). These procedures are able to reduce complexity and to arrive at “configurational” solutions based on set theory and Boolean algebra, which are more meaningful in this context than the usual broad-based statistical methods. In the last section, these methods are contrasted with more common statistical comparative methods at the macro-level of states or societies and the respective strengths and weaknesses are discussed. Some basic quantitative or qualitative methodological training is probably useful to get more out of the course, but participants with little methodological training should find no major obstacles to follow.

An introduction to Comparative Research

This module presents fundamental notions of comparative research designs. To begin with, you will be introduced to multi-dimensional matters. Subsequently, you will delve into John Stuart Mill’s methods and limitations.

What's included

6 videos 10 readings 2 quizzes

6 videos • Total 41 minutes

• Multi-dimensional substance matter • 7 minutes • Preview module
• The plastic matter of social sciences • 9 minutes
• Linking levels of analysis • 6 minutes
• Mill's canons • 5 minutes
• Mill‘s methods: Pop's Seafood Platter • 4 minutes
• Mill's methods: limitations • 7 minutes

10 readings • Total 31 minutes

• Three Fundamental notions • 3 minutes
• Multi-dimensional substance matter • 4 minutes
• The plastic matter of social sciences • 4 minutes
• Qualitative Comparative Analysis • 3 minutes
• Linking levels of analysis • 2 minutes
• Coleman's "bathtub" • 3 minutes
• Pop's Seafood Platter • 3 minutes
• Mill's limitations • 3 minutes
• Mill's methods and recent advances • 1 minute

2 quizzes • Total 30 minutes

• Challenge yourself: Epistemological foundations of the social sciences • 15 minutes
• Challenge yourself: Mill's canon • 15 minutes

Comparative Research Designs

This module presents further advances in comparative research designs. To begin with, you will be introduced to case selection and types of research designs. Subsequently, you will delve into most similar and most different designs (MSDO/MDSO) and observe their operationalization.

6 videos 6 readings 2 quizzes

6 videos • Total 48 minutes

• Further advances • 7 minutes • Preview module
• Overview • 7 minutes
• Major steps of research process • 6 minutes
• MSDO/MDSO application • 8 minutes
• Operationalizing similarities and dissimilarities • 9 minutes
• Analysis and interpretation • 8 minutes

6 readings • Total 30 minutes

• Further advances • 4 minutes
• Overview of comparative research designs • 4 minutes
• Selection of variables and cases • 5 minutes
• Operationalizing similarities and dissimilarities • 5 minutes
• Analysis and interpretation • 6 minutes
• Challenge yourself: Further Advances, Comparative Research Designs • 15 minutes
• Challenge yourself: Most similar and most different designs • 15 minutes

QCA Analysis

This module presents Boolean Algebra and the main steps of QCA. The first lesson will introduce basic features of QCA and provide an example of such analysis. The second lesson will focus on QCA applications, troubleshooting, Multi-Value QCA (mv-QCA), and more specific features of QCA.

6 videos 7 readings 2 quizzes

6 videos • Total 40 minutes

• QCA Basics • 8 minutes • Preview module
• QCA Analysis • 9 minutes
• Simple paper and pencil example • 5 minutes
• Troubleshooting Contradictions • 6 minutes
• Threshold setting, necessary and sufficient conditions • 4 minutes
• Multi-Value QCA (mv-QCA) • 6 minutes

7 readings • Total 41 minutes

• QCA Basics • 7 minutes
• QCA Analysis pt.1 • 5 minutes
• QCA Analysis pt.2 • 7 minutes
• Simple paper and pencil example • 7 minutes
• Troubleshooting Contradictions (C) • 6 minutes
• Threshold setting, necessary and sufficient conditions • 3 minutes
• Challenge yourself: Introduction to Boolean Algebra, main steps of QCA • 15 minutes
• Challenge yourself: QCA applications, troubleshooting, Multi-Value QCA (mv-QCA) • 15 minutes

Fuzzy set analyses

This module presents the basic features of the fuzzy set analyses and application, and analyzes in greater depth QCA. The first lesson will introduce basic features of fuzzy set analyses and provide examples of such analysis. The second lesson will focus on fuzzy set applications, its purposes and advantages, and explores more specific features of QCA.

6 videos • Total 37 minutes

• Fuzzy sets • 6 minutes • Preview module
• Calculation of necessary and sufficient conditions • 3 minutes
• Fuzzy sets. Relationship between condition and outcome as in a triangular scatterplot • 3 minutes
• Principles • 6 minutes
• Lipset's conditions • 7 minutes
• Conclusions • 9 minutes

7 readings • Total 75 minutes

• Fuzzy sets • 10 minutes
• Calculation of necessary and sufficient conditions • 10 minutes
• Fuzzy sets. Relationship between condition and outcome as in a triangular scatterplot • 10 minutes
• Principles • 10 minutes
• Cases • 5 minutes
• Examples • 15 minutes
• Conclusions • 15 minutes
• Challenge yourself: Fuzzy set analyses, basic features • 15 minutes
• Challenge yourself: Fuzzy set applications (fs/qca) • 15 minutes

Macro-quantitative (statistical): Methods and perspectives

This module presents the macro-quantitative (statistical) methods by giving examples of recent research employing them. It analyzes the regression analysis and the various ways of analyzing data. Moreover, it concludes the course and opens to further perspectives on comparative research designs and methods.

6 videos • Total 45 minutes

• Data • 7 minutes • Preview module
• Examples • 6 minutes
• Regression analysis • 6 minutes
• Summary • 8 minutes
• Contrasting macro qualitative and quantitative methods • 8 minutes
• Continuing debates: prospects • 6 minutes

6 readings • Total 75 minutes

• Data • 10 minutes
• Examples • 10 minutes
• Regression analysis • 10 minutes
• Summary • 15 minutes
• Contrasting macro qualitative and quantitative methods • 15 minutes
• Continuing debates, prospects • 15 minutes
• Challenge yourself: Macro-quantitative (statistical) Methods • 15 minutes
• Challenge yourself: Conclusions and Perspectives • 15 minutes

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Comparative methods

Tags_migration, old_description, description.

Comparative method is about looking at an object of study in relation to another. The object of study is normally compared across space and/or time. Comparative methods can be qualitative and quantitative. Often, there is a trade-off: the more cases to compare, the less comparable variables available and vice versa.

The comparative method is often applied when looking for patterns of similarities and differences, explaining continuity and change. Often applied in comparative research is the Most Similar Systems Design (that consists in comparing very similar cases that differ in the dependent variable, on the assumption that this will make it easier to find those independent variables which explain the presence/absence of the dependent variable) or the Most Different Systems Design (comparing very different cases, all of which have the same dependent variable in common, so that any other circumstance that is present in all the cases can be regarded as the independent variable).

A challenge in comparative research is that what may seem as the same category across countries may in fact be defined very differently in these same countries.

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• Open access
• Published: 06 May 2024

Mid-term outcomes of laparoscopic vaginal stump?round (Kakinuma method) and stump?uterosacral (Shull method) ligament fixation for pelvic organ prolapse: a retrospective comparative study

• Toshiyuki Kakinuma 1 ,
• Kaoru Kakinuma 1 ,
• Kyouhei Ueyama 1 ,
• Takumi Shinohara 1 ,
• Rora Okamoto 1 ,
• Ken Imai 1 ,
• Nobuhiro Takeshima 1 ,
• Kaoru Yanagida 1 &
• Michitaka Ohwada 1  

BMC Surgery volume  24 , Article number:  137 ( 2024 ) Cite this article

164 Accesses

Metrics details

Laparoscopic sacrocolpopexy (LSC) and robot-assisted sacrocolpopexy (RSC) using mesh are popular approaches for treating pelvic organ prolapse (POP). However, it is not uncommon that native tissue repair (NTR) should be presented as an option to patients who are expected to have extensive intraperitoneal adhesion or patients for whom LSC or RSC is difficult owing to various risk factors. Laparoscopic vaginal stump–uterosacral ligament fixation (Shull method) has been introduced as a method for NTR in case of POP. However, effective repair using this surgical procedure may not be possible in severe POPs. To solve the problems of the Shull method, we devised the laparoscopic vaginal stump–round ligament fixation (Kakinuma method) in which the vaginal stump is fixed to the uterine round ligament, a histologically strong tissue positioned anatomically higher than the uterosacral ligament. This study aimed to retrospectively and clinically compare the two methods.

Of the 78 patients who underwent surgery for POP between January 2017 and June 2022 and postoperative follow-up for at least a year, 40 patients who underwent the Shull method (Shull group) and 38 who underwent the Kakinuma method (Kakinuma group) were retrospectively analyzed.

No significant differences were observed between the two groups in patient background variables such as mean age, parity, body mass index, and POP-Q stage. The mean operative duration and mean blood loss in the Shull group were 140.5 ± 31.7 min and 91.3 ± 96.3 ml, respectively, whereas the respective values in the Kakinuma group were 112.2 ± 25.3 min and 31.4 ± 47.7 ml, respectively. Thus, compared with the Shull group, the operative duration was significantly shorter ( P  < 0.001) and blood loss was significantly less ( P  = 0.003) in the Kakinuma group. Recurrence was observed in six patients (15.0%) in the Shull group and two patients (5.3%) in the Kakinuma group. Hence, compared with the Shull group, recurrence was significantly less in the Kakinuma group ( P  = 0.015). No patients experienced perioperative complications in either group.

Conclusions

The results suggest that the Kakinuma method can serve as a novel and viable NTR procedure for POP.

Peer Review reports

Pelvic organ prolapse (POP) is the abnormal positioning of pelvic organs in which pelvic organs, such as the bladder, uterus, rectum, and vaginal wall, drop and prolapse through the vaginal opening owing to a decrease in the supporting ability of pelvic floor muscles. Lifestyle habits that cause abdominal pressure, such as aging, childbirth, intense exercise, labor, and constipation, and decrease in female hormones are reportedly involved [ 1 , 2 , 3 ]. These factors cause the loosening of pelvic floor muscles and endopelvic fascia, leading to the abnormal positioning of pelvic organs, often manifesting as pelvic floor hernia.

According to an epidemiological survey in the United States and a European country, 44% of parous women had POP [ 4 ] and 11% had received surgery for POP or urinary incontinence by the age of 80 years [ 5 , 6 ]. A more recent epidemiological survey has reported an even higher percentage; 20% of women had received these surgeries by the age of 80 years [ 7 ]. According to a report in Japan, POP was observed in approximately 17% of women aged 21–84 years [ 8 ]. As the mean life expectancy of women has increased in recent years, this disease is expected to increase in the future. POP tends to occur among women in middle and advanced age, and it greatly deteriorates their quality of life (QOL).

The treatment of POP aims to resolve serious symptoms, such as lower urinary tract symptoms, sexual dysfunction, and a feeling of organ prolapse, and improve the QOL by correcting organ positioning. Surgical therapy is selected when pessary insertion causes complications, such as vaginal ulcers, or when QOL does not improve after conservative therapy [ 9 ]. Conventionally, anterior/posterior colporrhaphy has long been performed as a surgical intervention after vaginal total hysterectomy. However, this surgical procedure is associated with issues, such as a high recurrence rate and the lack of consideration for postoperative sexual function [ 5 , 10 , 11 , 12 ].

With the recent introduction of mesh surgery (Tension-free vaginal mesh: TVM), surgical interventions for POP have advanced dramatically. However, the use of surgical mesh received a warning from the United States Food and Drug Administration (FDA) as it was associated with various problems, such as postoperative infection and dyspareunia owing to mesh detachment, erosion, and hardening [ 13 ]. Moreover, mesh surgery is difficult owing to risk factors, for patients who are expected to have extensive intraperitoneal adhesion and those with increased susceptibility to infection. These factors pose a high risk for developing erosion and infections as mesh-specific complications. As a result, active interest in native tissue repair (NTR) has been revived. The NTR procedures include vaginal stump–uterosacral ligament fixation (Shull method) reported by Shull et al. in which the vaginal canal axis is reconstructed without a mesh as in laparoscopic sacrocolpopexy (LSC) [ 14 ]. However, effective repair may not be achievable by simply fixing the vaginal stump and the uterosacral ligament in severe POPs in which the vaginal canal is long or when the uterosacral ligament is overextended or weakened.

To solve this problem, we have devised and reported laparoscopic vaginal stump–round ligament fixation (Kakinuma method) as a new NTR procedure for patients with POP [ 15 ]. The uterine round ligament is a histologically strong tissue positioned anatomically even higher than the uterosacral ligament. Moreover, when the uterine round ligament is overextended, adjustment can be easily made by resecting the extended round ligament so that the vaginal stump is raised 4–5 cm from the vaginal opening before it is fixed and sutured to the uterine round ligament.

This study aimed to retrospectively and clinically compare the conventional Shull method and the Kakinuma method as NTR procedures in patients with POP.

This study was approved by the Ethics Committee of the International University of Health and Welfare (approval number: 21-B-463). Treatment was provided to all the patients after obtaining their informed consent via an adequate informed consent process. Of a total of 78 patients who underwent surgical treatment for the diagnosis of POP between January 2017 and June 2022 and follow-up observation for at least 12 months after surgery, 40 patients who underwent the Shull method (Shull group) and 38 patients who underwent the Kakinuma method (Kakinuma group) were retrospectively analyzed. Surgical outcomes were examined based on their medical records, including age, gravida and parity, comorbidities, POP-Q stage (Table  1 ) [ 16 ], operative duration, blood loss, intraoperative complications, and incidence of recurrence.

At the beginning of the surgery, patients in both groups were placed in the lithotomy position under general anesthesia. Both methods were performed in a 20° head-down position using a 10-mm 0° rigid scope with a pneumoperitoneum pressure of 10 mmHg. Using the open approach method, the trocars were placed in a diamond configuration, with a 12-mm camera port at the umbilical area and 5-mm ports at three sites in the lower abdomen; the surgical trocars were positioned 3 cm medial to the anterior superior iliac spines and their midpoint. After incising the vesicouterine pouch, the round and infundibulopelvic ligaments were cut. After identifying the uterine artery and the ureter, the main trunk of the uterine artery was ligated. The bladder was separated from the cervix, and bilateral cardinal ligaments and parauterine tissues were ligated and cut. The vaginal canal was released from the posterior vaginal fornix and then circumferentially incised from the vaginal lumen along the vaginal portion of the cervix before the uterus was transvaginally removed. The vaginal stump was closed using a continuous suture with 1 − 0 absorbable thread (Ti-Cron™, Covidien Japan Co, Japan).

In the Shull method, after the uterosacral ligament was identified, the ureter was identified and separated by approaching along the uterosacral ligament from the lateral peritoneum to the retroperitoneal cavity. Suturing was done using 2 − 0 delayed absorbable thread (Ti-Cron™, Covidien Japan Co, Japan) by passing the needle sequentially from the anterior vaginal wall of the right vaginal stump to the posterior vaginal wall and the distal end of the right uterosacral ligament (Fig.  1 a, b). Suture fixation was done so that the center of the vaginal stump was placed at the center of the uterosacral ligament. Similarly, the left vaginal stump and the left uterosacral ligament were sutured and fixed using 2 − 0 delayed absorbable thread (Ti-Cron™, Covidien Japan Co, Japan) (Fig.  1 c, d).

• Shull method

Suturing was done using 2 − 0 delayed absorbable thread by passing the needle sequentially from the anterior vaginal wall of the vaginal stump to the posterior vaginal wall and the distal end of the right uterosacral ligament ( a, b ), and suture fixation was done so that the center of the vaginal stump was placed at the center of the uterosacral ligament. Similarly, the left vaginal stump and the left uterosacral ligament were sutured and fixed using 2 − 0 delayed absorbable thread ( c, d )

In the Kakinuma method, suturing was done using 2 − 0 delayed absorbable thread (Ti-Cron™, Covidien Japan Co, Japan) by passing the needle sequentially from the anterior vaginal wall of the right vaginal stump to the posterior vaginal wall and the distal end of the right uterine round ligament (Fig.  2 a, b). Suture fixation was done so that the center of the vaginal stump was placed at the center of the uterine round ligament. Similarly, the left vaginal stump and the left uterine round ligament were sutured and fixed using 2 − 0 delayed absorbable thread (Ti-Cron™, Covidien Japan Co, Japan) (Fig.  2 c, d). In cases where the round ligaments were overextended, the redundant round ligaments were shortened via resection so that the vaginal stump was positioned 4–5 cm from the vaginal opening, and the vaginal stump was sutured to the round ligament.

• Kakinuma method

Suturing was done using 2 − 0 delayed absorbable thread by passing the needle sequentially from the anterior vaginal wall of the vaginal stump to the posterior vaginal wall and the distal end of the right uterine round ligament ( a, b ). The center of the vaginal stump and the proximal end of the uterine round ligament were sutured and fixed so that the vaginal stump was positioned 4–5 cm from the vaginal opening. Similarly, the left vaginal stump and the left uterine round ligament were sutured and fixed using 2 − 0 delayed absorbable thread ( c, d )

In both groups, after vaginal stump fixation, the retroperitoneum was closed by continuous suturing. After confirming that there was no bleeding in the abdominal cavity, an adhesion-preventing agent (AdSpray®, Terumo Corporation, Tokyo, Japan) was sprayed, and the surgery was completed.

In statistical analysis, continuous variables were compared using the Mann–Whitney U test and categorical variables were compared using the Fisher’s exact test. P  < 0.05 was considered to indicate that the difference was statistically significant.

A total of 78 cases were included, comprising 40 cases in which the Shull method was used (Shull group) and 38 cases in which the Kakinuma method was used (Kakinuma group). Patient background data are shown in Table  2 . No significant differences were observed between the two groups in patient background data, such as the mean age, parity, BMI, and POP-Q stage. Surgical outcomes are shown in Table  3 . The mean operative duration and mean blood loss in the Shull group were 140.5 ± 31.7 min and 91.3 ± 96.3 ml, respectively, whereas the respective values in the Kakinuma group were 112.2 ± 25.3 min and 31.4 ± 47.9 ml, respectively. Thus, the Kakinuma procedure was completed in a significantly shorter time ( P  < 0.001) and was associated with a smaller bleeding volume ( P  = 0.003) compared with the Shull procedure. The postoperative observation period was 23.5 ± 8.0 months in the Shull group and 23.4 ± 7.3 months in the Kakinuma group, with no significant difference ( P  = 0.964). Recurrence of POP was observed in six patients (15.0%) in the Shull group and two patients (5.3%) in the Kakinuma group. Hence, recurrence was significantly less frequent in the latter group ( P  = 0.015). No perioperative complications were observed in either group.

This study compared laparoscopic vaginal stump–round ligament fixation (Kakinuma method) as a new NTR for POP with the Shull method as a conventional NTR in terms of usefulness and safety. The treatment of POP aims to mitigate symptoms by anatomically restoring the abnormal positioning of the prolapsed organs. Conservative therapies include physical methods, such as pelvic floor muscle exercises, and noninvasive recovery methods using pessaries. However, for moderate to severe POP, surgical therapy must be selected. Most patients with this disease are older people and have decreased overall functional capacities, such as decreased organ reserve, wound healing, and immune capacities, as well as comorbidities. Thus, the procedure for surgical therapy should be selected based on patient background factors, such as general condition.

Conventionally, vaginal total hysterectomy and colporrhaphy have been widely performed as surgical therapies for POP. However, it is difficult to repair POP by simply dissecting excess mucous membrane of the vaginal wall and suture repairing, and the recurrence rate has been reported to be high [ 5 , 10 , 11 , 12 ].

Subsequently, the tension-free vaginal mesh (TVM) procedure in which a mesh is used to replace the pubocervical fascia and rectovaginal fascia, which are the most important supporting structures in the pelvic floor, has been reported and used mainly in the field of urology [ 17 ]. This surgery, which was introduced in the United States and European countries in 2000, restores the dropped uterus and bladder to the original position and reinforces them using a polypropylene mesh specifically for POP surgery. TVM gained popularity because of reduced postoperative pain and low recurrence rate. However, FDA issued a warning because it caused serious complications, such as mesh exposure to the vagina and bladder/rectal injuries [ 13 ], and mesh for TVM surgery to treat POP was discontinued in 2012.

Meanwhile, a surgical procedure that raises the vaginal stump to the promontorium abdominally was reported in 1957, and with the subsequent widespread use of the mesh, abdominal sacrocolpopexy was developed. However, it was not commonly used because the procedure was highly invasive, and intraoperative complications, such as major bleeding from the sacrum, were reported [ 18 , 19 ]. However, with the development of laparoscopic techniques, LSC is becoming popular as it is less invasive and has shown therapeutic effectiveness comparable to that of laparotomy [ 20 ]. However, there are many cases in which mesh surgery is difficult to select because of risk factors, including patients expected to have severe intraperitoneal adhesion and, as mentioned above, patients at a high risk of developing erosion and infection owing to increased susceptibility to infection. For these reasons, NTR has regained the importance in the treatment of POP [ 21 , 22 ]. The standard surgical procedure of NTR is based on the vaginal technique, and vaginal stump fixation is performed after total hysterectomy. Vaginal stump fixation methods include the Shull method in which the stump is fixed to the uterosacral ligament [ 14 ]. This method is characterized by the elevation of the vaginal canal in a physiological direction; however, there is a risk of ureteral injury or obstruction as the ureter is in close proximity to the uterosacral ligament. Moreover, effective repair may not be achievable by simply fixing the vaginal stump and the uterosacral ligament in patients with severe POP because the vaginal canal is long and in patients with an overextended or weakened uterosacral ligament. Therefore, to solve these problems, we devised the Kakinuma method as a safe and effective NTR procedure. In this surgical procedure, the vaginal stump is fixed to the uterine round ligament, which is anatomically higher and histologically stronger and has no vital organs in the adjacent areas, after laparoscopic total hysterectomy [ 17 , 23 ]. Historically, POP surgery has been performed transvaginally; however, it is not easy to acquire sufficient skills to perform this procedure owing to the narrow visual field. The use of laparoscopy allows the sharing of a clear, magnified visual field with the surgical staff. Moreover, as laparoscopic total hysterectomy has recently become a basic surgical procedure for obstetricians and gynecologists, no new special surgical equipment or tool is required. Furthermore, the procedure is not so technically demanding and has minimal effects from surgeons’ skill levels because there are no important organs around the uterine round ligament. In this study, no surgical complications were observed in the cases analyzed. Another advantage is that this surgical procedure has minimal intraoperative complication risks, such as organ injuries during retroperitoneal tunnel creation for mesh insertion and vascular injuries during fixation of the mesh to the anterior longitudinal ligament of the sacral promontory in LSC [ 24 , 25 , 26 ]. When it is desirable to avoid LSC for reasons such as adhesion, it is possible to immediately switch to this method.

In patients with an overextended uterine round ligament, the vaginal stump can be effectively lifted by fixing the vaginal stump after resecting the redundant uterine round ligament so that it is positioned 4–5 cm from the vaginal opening.

In this study, the Kakinuma method for POP was completed in a significantly shorter time with a smaller bleeding volume and a lower recurrence rate compared with the conventional Shull method. The results suggest that it could be a new NTR procedure for POP. However, a limitation of this surgical procedure is that this procedure alone may not suffice. Its use as a hybrid method with conventional transvaginal colporrhaphy and perineoplasty, such as levatorplasty, may be required when further reinforcement of the posterior vaginal wall is needed or if the patients have cystocele or rectocele.

This study included patients who underwent follow-up observation for at least 12 months after the surgery. This was a single-center retrospective study in a small number of patients. In the future, it is necessary to accumulate more cases and perform follow-up evaluation for a longer term. Therefore, it is important to evaluate cases in detail from various aspects, such as recurrence and late postoperative complications, and determine the criteria of indication for this surgical procedure.

Treatment of POP using the Kakinuma method was completed in a significantly shorter time with a smaller bleeding volume and a lower recurrence rate compared with the conventional Shull method. The results shown here suggest that this surgical procedure could be a new option of NTR for POP.

Data availability

All data generated or analyzed during this study are included in this article. Further inquiries can be directed to the corresponding author at [email protected].

Abbreviations

Food and Drug Administration

• Native tissue repair
• Pelvic organ prolapse

Quality of life

Total abdominal hysterectomy

Total laparoscopic hysterectomy

Tension-free vaginal mesh

Gyhagen M, Åkervall S, Milsom I. Clustering of pelvic floor disorders 20 years after one vaginal or one cesarean birth. Int Urogynecol J. 2015;26:1115–21.

Article   PubMed   Google Scholar  

Ng K, Cheung RYK, Lee LL, Chung TKH, Chan SSC. An observational follow-up study on pelvic floor disorders to 3–5 years after delivery. Int Urogynecol J. 2017;28:1393–9.

Gyhagen M, Bullarbo M, Nielsen TF, Milsom I. Prevalence and risk factors for pelvic organ prolapse 20 years after childbirth: a national cohort study in singleton primiparae after vaginal or caesarean delivery. BJOG. 2013;120:152–60.

Article   CAS   PubMed   Google Scholar  

Samuelsson EC, Arne Victor FT, Tibblin G, Svärdsudd KF. Signs of genital prolapse in a Swedish population of women 20 to 59 years of age and possible related factors. Am J Obstet Gynecol. 1999;180:299–305.

Olsen AL, Smith VJ, Bergstrom JO, Colling JC, Clark AL. Epidemiology of surgically managed pelvic organ prolapse and urinary incontinence. Obstet Gynecol. 1997;89:501–6.

Fialkow MF, Newton KM, Lentz GM, Weiss NS. Lifetime risk of surgical management for pelvic organ prolapse or urinary incontinence. Int Urogynecol J Pelvic Floor Dysfunct. 2008;19:437–40.

Wu JM, Matthews CA, Conover MM, Pate V, Jonsson Funk M. Lifetime risk of stress urinary incontinence or pelvic organ prolapse surgery. ObstetGynecol. 2014;123:1201–6.

Google Scholar  

Kato J, Nagata C, Miwa K, Ito N, Morishige KI. Pelvic organ prolapse and Japanese lifestyle: prevalence and risk factors in Japan. Int Urogynecol J. 2022;33:47–51.

Doaee M, Moradi-Lakeh M, Nourmohammadi A, Razavi-Ratki SK, Nojomi M. Management of pelvic organ prolapse and quality of life: a systematic review and meta-analysis. Int Urogynecol J. 2014;25:153–63.

Auwad W, Bombieri L, Adekanmi O, Waterfield M, Freeman R. The development of pelvic organ prolapse after colposuspension: a prospective, long-term follow-up study on the prevalence and predisposing factors. Int Urogynecol J Pelvic Floor Dysfunct. 2006;17:389–94.

Whiteside JL, Weber AM, Meyn LA, Walters MD. Risk factors for prolapse recurrence after vaginal repair. Am J Obstet Gynecol. 2004;191:1533–8.

Bump RC, Mattiasson A, Bø K, Brubaker LP, DeLancey JO, Klarskov P, et al. The standardization of terminology of female pelvic organ prolapse and pelvic floor dysfunction. Am J Obstet Gynecol. 1996;175:10–7.

FDA. FDA takes action to protect women’s health, orders manufacturers of surgical mesh intended for transvaginal repair of pelvic organ prolapse to stop selling all devices. 2019 https://www.fda.gov/news-events/press-announcements/fda-takes-action-protect-womens-health-ordersmanufacturers-surgical-mesh-intended-transvaginal Access October 4,2023.

Shull BL, Bachofen C, Coates KW, Kuehl TJ. A transvaginal approach to repair of apical and other associated sites of pelvic organ prolapse with uterosacral ligaments. Am J Obstet Gynecol Am J Obstet Gynecol. 2000;183:1365–73. discussion 1373–4.

Kakinuma T, Kaneko A, Kakinuma K, Imai K, Takeshima N, Ohwada M. New native tissue repair forpelvic organ prolapse: medium-term outcomes of laparoscopic vaginal stump–round ligament fixation. World J Clin Cases. 2023;11:3457–63.

Article   PubMed   PubMed Central   Google Scholar  

Persu C, Chapple CR, Cauni V, Gutue S, Geavlete P. Pelvic organ prolapse quantification system (POP-Q) - a new era in pelvic prolapse staging. J Med Life. 2011;4:75–81.

CAS   PubMed   PubMed Central   Google Scholar  

Debodinance P, Berrocal J, Clavé H, Cosson M, Garbin O, Jacquetin B, et al. Changing attitudes on the surgical treatment of urogenital prolapse: birth of the tension-free vaginal mesh. J Gynecol Obstet Biol Reprod (Paris). 2004;33:577–88.

Gadonneix P, Ercoli A, Scambia G, Villet R. The use of laparoscopic sacrocolpopexy in the management of pelvic organ prolapse. Curr Opin Obstet Gynecol. 2005;17:376–80.

Coolen AWM, van Oudheusden AMJ, Mol BWJ, van Eijndhoven HWF, Roovers JWR, Bongers MY. Laparoscopic sacrocolpopexy compared with open abdominal sacrocolpopexy for vault prolapse repair: a randomised controlled trial. Int Urogynecol J. 2017;28:1469–79.

Freeman RM, Pantazis K, Thomson A, Frappell J, Bombieri L, Moran P, et al. A randomised controlled trial of abdominal versus laparoscopic sacrocolpopexy for the treatment of post-hysterectomy vaginal vault prolapse: LAS study. Int Urogynecol J. 2013;24:377–84.

Sassani JC, Artsen AM, Moalli PA, Bradley MS. Temporal trends of urogynecologic mesh reports to the U.S. food and drug administration. Obstet Gynecol. 2020;135:1084–90.

Braga A, Serati M, Salvatore S, Torella M, Pasqualetti R, Papadia A, et al. Update in native tissue vaginal vault prolapse repair. Int Urogynecol J. 2020;31:2003–10.

Bellier A, Cavalié G, Marnas G, Chaffanjon P. The round ligament of the uterus: questioning its distal insertion. Morphologie. 2018;102:55–60.

Paul S. Bilateral round igament suspension (RLS) of the vinal vault during total abdominal hysterectomy (TAH) or total laparoscopic hysterectomy (TLH) to prevent post hysterectomy vault prolapse (PHVP)–An innovative surgical technique. Obstet Gynecol Int J. 2016;5:00150.

Article   Google Scholar  

Sutton GP, Addison WA, Livengood CH, Hammond CB. Life-threatening hemorrhage complicating sacral colpopexy. Am J Obstet Gynecol. 1981;140:836–7.

Ganatra AM, Rozet F, Sanchez-Salas R, Barret E, Galiano M, Cathelineau X, Vallancien G. Current status of laparoscopic sacrocolpopexy: a review. Eur Urol. 2009;55:1089–103.

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Kakinuma, T., Kakinuma, K., Ueyama, K. et al. Mid-term outcomes of laparoscopic vaginal stump?round (Kakinuma method) and stump?uterosacral (Shull method) ligament fixation for pelvic organ prolapse: a retrospective comparative study. BMC Surg 24 , 137 (2024). https://doi.org/10.1186/s12893-024-02429-9

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• Published: 13 May 2024

Ethnography and ethnohistory support the efficiency of hunting through endurance running in humans

• Eugène Morin   ORCID: orcid.org/0000-0002-4840-0156 1 , 2 &
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Humans have two features rare in mammals: our locomotor muscles are dominated by fatigue-resistant fibres and we effectively dissipate through sweating the metabolic heat generated through prolonged, elevated activity. A promising evolutionary explanation of these features is the endurance pursuit (EP) hypothesis, which argues that both traits evolved to facilitate running down game by persistence. However, this hypothesis has faced two challenges: running is energetically costly and accounts of EPs among late twentieth century foragers are rare. While both observations appear to suggest that EPs would be ineffective, we use foraging theory to demonstrate that EPs can be quite efficient. We likewise analyse an ethnohistoric and ethnographic database of nearly 400 EP cases representing 272 globally distributed locations. We provide estimates for return rates of EPs and argue that these are comparable to other pre-modern hunting methods in specified contexts. EP hunting as a method of food procurement would have probably been available and attractive to Plio/Pleistocene hominins.

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Isotopic evidence of high reliance on plant food among Later Stone Age hunter-gatherers at Taforalt, Morocco

Skeletal muscle energy metabolism during exercise

Data availability.

All data presented in the paper are available in Supplementary Data 1 , along with citations to their sources.

Bramble, D. M. & Lieberman, D. E. Endurance running and the evolution of Homo . Nature 432 , 345–352 (2004).

Article   CAS   PubMed   Google Scholar  

Pontzer, H. Economy and endurance in human evolution. Curr. Biol. 27 , R613–R621 (2017).

Lieberman, D. E. Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding (Pantheon Books, 2020).

Carrier, D. R. The energetic paradox of human running and hominid evolution. Curr. Anthropol. 25 , 483–495 (1984).

Article   Google Scholar  

Bogdanis, G. C., Nevill, M., Lakomy, H. & Boobis, L. Power output and muscle metabolism during and following recovery from 10 and 20s of maximal sprint exercise in humans. Acta Physiol. Scand. 163 , 261–272 (1998).

Calbet, J. A. L. et al. Limitations to oxygen transport and utilization during sprint exercise in humans: evidence for a functional reserve in muscle O 2 diffusing capacity. J. Physiol. 593 , 4649–4664 (2015).

Article   CAS   PubMed   PubMed Central   Google Scholar  

Sharp, N. C. C. Timed running speed of a cheetah ( Acinonyx jubatus ). J. Zool. 241 , 493–494 (1997).

O’Neill, M. C., Umberger, B. R., Holowka, N. B., Larson, S. G. & Reiser, P. J. Chimpanzee super strength and human skeletal muscle evolution. Proc. Natl Acad. Sci. USA 114 , 7343–7348 (2017).

Article   PubMed   PubMed Central   Google Scholar  

Queeno, S. R. et al. Human and African ape myosin heavy chain content and the evolution of hominin skeletal muscle. Comp. Biochem. Physiol. A https://doi.org/10.1016/j.cbpa.2023.111415 (2023).

Baker, J. S., McCormick, M. C. & Robergs, R. A. Interaction among skeletal muscle metabolic energy systems during intense exercise. J. Nutr. Metab. 2010 , 905612 (2010).

Mukund, K. & Subramaniam, S. Skeletal muscle: a review of molecular structure and function, in health and disease. Syst. Biol. Med. 12 , e1462 (2020).

Google Scholar  

Best, A. W. Why does strength training improve endurance performance? Am. J. Hum. Biol. 33 , e23526 (2020).

Article   PubMed   Google Scholar  

Schmidt-Nielsen, K. Desert Animals: Physiological Problems of Heat and Water (Clarendon Press, 1964).

Speakman, J. R. & Król, E. Maximal heat dissipation capacity and hyperthermia risk: neglected key factors in the ecology of endotherms. J. Anim. Ecol. 79 , 726–746 (2010).

Kamberov, Y. G. et al. Comparative evidence for the independent evolution of hair and sweat gland traits in primates. J. Hum. Evol. 125 , 99–105 (2018).

Saris, W. H. M. The role of sports foods in physical performance. in International Food Safety Handbook: Science, International Regulation, and Control (eds van der Heijden, K., Younes, M., Fishbein, L. & Miller, S.) Ch. 13 (CRC Press, 1999).

Newman, R. W. Why man is such a sweaty and thirsty naked animal: a speculative review. Hum. Biol. 42 , 12–27 (1970).

CAS   PubMed   Google Scholar  

Aldea, D. et al. Repeated mutation of a developmental enhancer contributed to human thermoregulatory evolution. Proc. Natl Acad. Sci. 118 , e2021722118 (2021).

Kamberov, Y. G. et al. A genetic basis of variation in eccrine sweat gland and hair follicle density. Proc. Natl Acad. Sci. USA 112 , 9932–9937 (2015).

Godfrey, R. W. et al. Evaluating the impact of breed, pregnancy, and hair coat on body temperature and sweating rate of hair sheep ewes in the tropics. J. Anim. Sci. 95 , 2936–2942 (2017).

Asres, A. & Amha, N. Physiological adaptation of animals to the change of environment: a review. J. Biol. Agric. Healthc. 4 , 146–151 (2014).

Hora, M., Pontzer, H., Struška, M., Entin, P. & Sládek, V. Comparing walking and running in persistence hunting. J. Hum. Evol. 172 , 103247 (2022).

Montagu, A. Natural selection and man’s relative hairlessness. JAMA 187 , 356–357 (1964).

Krantz, G. S. Brain size and hunting ability in earliest man. Curr. Anthropol. 9 , 450–451 (1968).

Watanabe, H. Running, creeping and climbing: a new ecological and evolutionary perspective on human locomotion. Mankind 8 , 1–13 (1971).

Bortz, W. M. Physical exercise as an evolutionary force. J. Hum. Evol. 14 , 145–155 (1985).

MacArthur, R. H. & Pianka, E. R. On optimal use of a patchy environment. Am. Nat. 100 , 603–609 (1966).

Bramble, D. M. & Carrier, D. R. Running and breathing in mammals. Science 219 , 251–256 (1983).

Lieberman, D. E., Bramble, D. M., Raichlen, D. A. & Shea, J. J. in The First Humans - Origin and Early Evolution of the Genus Homo (eds Grine, F. E. et al.) 77–92 (Springer, 2009).

Liebenberg, L. Persistence hunting by modern hunter‐gatherers. Curr. Anthropol. 47 , 1017–1026 (2006).

Liebenberg, L. The relevance of persistence hunting to human evolution. J. Hum. Evol. 55 , 1156–1159 (2008).

Hora, M., Pontzer, H., Wall-Scheffler, C. M. & Sládek, V. Dehydration and persistence hunting in Homo erectus . J. Hum. Evol. 138 , 102682 (2020).

Ruxton, G. D. & Wilkinson, D. M. Endurance running and its relevance to scavenging by early hominins. Evolution 67 , 861–867 (2013).

Glaub, M. & Hall, C. A. S. Evolutionary implications of persistence hunting: an examination of energy return on investment for !Kung hunting. Hum. Ecol. 45 , 393–401 (2017).

Vidal-Cordasco, M., Rodriguez, J., Prado-Novoa, O., Zorrilla-Revilla, G. & Mateos, A. Locomotor economy and foraging ecology in hominins. J. Anthropol. Res. 77 , 338–361 (2021).

Lieberman, D. E., Bramble, D. M., Raichlen, D. A. & Shea, J. J. The evolution of endurance running and the tyranny of ethnography: a reply to Pickering and Bunn (2007). J. Hum. Evol. 53 , 439–442 (2007).

Marino, F. E., Sibson, B. E. & Lieberman, D. E. The evolution of human fatigue resistance. J. Comp. Physiol. B 192 , 411–422 (2022).

Pickering, T. R. & Bunn, H. T. The endurance running hypothesis and hunting and scavenging in savanna-woodlands. J. Hum. Evol. 53 , 434–438 (2007).

Rathkey, J. K. & Wall‐Scheffler, C. M. People choose to run at their optimal speed. Am. J. Phys. Anthropol. 163 , 85–93 (2017).

Steudel-Numbers, K. L. & Wall-Scheffler, C. M. Optimal running speed and the evolution of hominin hunting strategies. J. Hum. Evol. 56 , 355–360 (2009).

Lieberman, D. E. et al. Running in Tarahumara (Rarámuri) culture: persistence hunting, footracing, dancing, work, and the fallacy of the athletic savage. Curr. Anthropol. 61 , 356–379 (2020).

Morin, E., Bird, D., Winterhalder, B. & Bliege Bird, R. Deconstructing hunting returns: can we reconstruct and predict payoffs from pursuing prey? J. Archaeol. Method Theory 29 , 561–623 (2022).

Schoener, T. W. The compression hypothesis and temporal resource partitioning. Proc. Natl Acad. Sci. USA 71 , 4169–4172 (1974).

Ember, C. R. Cross-Cultural Research Methods (AltaMira Press, 2009).

Watts, J. et al. Building quantitative cross-cultural databases from ethnographic records: promise, problems and principles. Cross Cult. Res. 56 , 62–94 (2022).

Jackson, J. C. et al. Supernatural explanations across 114 societies are more common for natural than social phenomena. Nat. Hum. Behav. 7 , 707–717 (2023).

Baughman, M. In pursuit of an ancient pursuit. Sports Illustrated 48 , 45–46 (1978).

Parker, K. L. & Robbins, C. T. Thermoregulation in mule deer and elk. Can. J. Zool. 62 , 1409–1422 (1984).

Morin, E., Bird, D., Winterhalder, B. & Bliege Bird, R. Why do humans hunt cooperatively? Ethnohistoric data reveal the contexts, advantages and evolutionary importance of communal hunting. Curr. Anthropol. (in the press).

Bunn, H. T. & Pickering, T. R. Bovid mortality profiles in paleoecological context falsify hypotheses of endurance running–hunting and passive scavenging by early Pleistocene hominins. Quat. Res. 74 , 395–404 (2010).

Ross, C. T. & Winterhalder, B. Sit-and-wait versus active-search hunting: a behavioral ecological model of optimal search mode. J. Theor. Biol. 387 , 76–87 (2015).

Hitchcock, R. K. et al. The ethnoarchaeology of ambush hunting: a case study of ǂGi pan, Western Ngamiland, Botswana. Afr. Archaeol. Rev. 36 , 119–144 (2019).

Cher, P. H., Stewart, I. B. & Worringham, C. J. Minimum cost of transport in human running is not ubiquitous. Med. Sci. Sports Exerc. 47 , 307–314 (2015).

Selinger, J. C. et al. Running in the wild: energetics explain ecological running speeds. Curr. Biol. 32 , 2309–2315.e3 (2022).

Hassmén, P. Perceptual and physiological responses to cycling and running in groups of trained and untrained subjects. Eur. J. Appl. Physiol. Occup. Physiol. 60 , 445–451 (1990).

O’Connell, J. F., Hawkes, K. & Jones, N. B. Hadza scavenging: implications for Plio/Pleistocene hominid subsistence. Curr. Anthropol. 29 , 356–363 (1988).

Boesch, C. Cooperative hunting roles among Tai chimpanzees. Hum. Nat. 13 , 27–46 (2002).

Samuni, L., Wegdell, F. & Surbeck, M. Behavioural diversity of bonobo prey preference as a potential cultural trait. eLife 9 , e59191 (2020).

Durnin, J. V. G. A. & Passmore, R. Energy, Work and Leisure (Heinemann Educational Books, 1967).

McArdle, W. D., Katch, F. I. & Katch, V. L. Exercise Physiology: Nutrition, Energy, and Human Performance 7th edn (Wolters Kluwer, 2010).

Mason, M. H. The Arctic Forests (Hodder and Stoughton, 1924).

Howley, J. P. The Beothucks or Red Indians: The Aboriginal Inhabitants of Newfoundland (Cambridge Univ. Press, 1915).

Cabeza de Vaca, A. N. The Journey of Alvar Nuñez Cabeza de Vaca (The Rio Grande Press, 1964).

Kroeber, A. L. Handbook of the Indians of California Bulletin No. 78 (Bureau of American Ethnology, 1925).

Cook, W. A. Through the Wildernesses of Brazil by Horse, Canoe and Float (American Tract Society, 1909).

Kronenberg, A. & Schütze, F. Teda of Tibesti. in Wiener Beiträge zur Kulturgeschichte und Linguistik . HRAF ms: 1, 6, 144, 28 l. [Original: 14, 160, 17 end plates] (Verlag Ferdinand Berger, 1958).

St. John, S. Life in the Forests of the Far East; or Travels in Northern Borneo Vol. 2, 2nd edn, Revised (Smith, Elder and Co., 1863).

Dutton, C. E. Hawaiian Volcanoes (Government Printing Office, 1883).

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Acknowledgements

Financial support for this research was provided by a Trent internal SSHRC grant (no. 53-51637). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript. This study greatly benefited from discussions with and/or comments from the following people: A. Best, D. Bird, R. B. Bird, D. Bramble, D. Carrier, S. Gerety, M. Grote, M. Hora, J. C. Jackson, J. Koster, D. Lieberman, J. F. O’Connell, J. Speth, F. M. and A. Stein, M. Vidal-Cordasco and C. Wall-Scheffler. C. Wall-Scheffler generously provided the regression formula used in Fig. 1 and Supplementary Information .

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Physicochemical characterization of rice straw before and after alkali-assist photocatalytic pretreatment: a comparative analysis

• Addressing the Nexus: "Revolutionizing the Food Processing Technology: Cutting-edge Innovations to Reduce Environmental Impact"
• Published: 16 May 2024

Cite this article

• Nisha Sethi 1 ,
• Neha Luhach 1 ,
• Anita Singh Kirrolia 1 ,
• Asha Gupta 1 ,
• Narsi Ram Bishnoi 1 ,
• Sanju Bala Dhull 2 &
• Pawan Kumar Rose   ORCID: orcid.org/0000-0002-2496-7334 3  

The potential of alkali-assist photocatalytic (AAP) pretreatment to overcome the recalcitrant nature of lignocellulose biomass, i.e. rice straw (RS), was investigated in the present study. Box-Behenken Design (BBD) using standard response surface methodology (RSM) approach was considered to obtain optimal conditions for maximum delignification. The model was designed with three variables: alkali concentration (NaOH, 0–3% w/v), photocatalyst (TiO 2 NPs (titania nanoparticles), 0–1 g/L) and pretreatment time (30–240 min). The availability of cellulose was increased by 96.73%, while the concentration of lignin and hemicellulose decreased by 73.89%, and 71.79%, respectively, at a combination of 1.5% NaOH, 0.5 g/L TiO 2 NPs and 135 min pretreatment time. The structural and morphological alterations in the RS were assessed via Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) both before and after AAP pretreatment. The FTIR measurement indicated that the original RS included a significant quantity of lignin, which was eliminated after the pretreatment procedure. The XRD pattern demonstrates that cellulose crystallinity is significantly affected by the pretreatment. The SEM analysis revealed structural distortion and surface porosity from the pretreatment procedure.

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Aghbashlo M, Khounani Z, Hosseinzadeh-Bandbafha H, Gupta VK, Amiri H, Lam SS, Morosuk T, Tabatabaei M (2021) Exergoenvironmental analysis of bioenergy systems: a comprehensive review. Renew Sustain Energy Rev 149:111399. https://doi.org/10.1016/j.rser.2021.111399

Article   Google Scholar  

Amnuaycheewa P, Hengaroonprasan R, Rattanaporn K, Kirdponpattara S, Cheenkachorn K, Sriariyanun M (2016) Enhancing enzymatic hydrolysis and biogas production from rice straw by pretreatmentwithorganicacids. Ind Crops Prod 87:247–254. https://doi.org/10.1016/j.indcrop.2016.04.069

Article   CAS   Google Scholar  

Baksi S, Saha D, Saha S, Sarkar U, Basu D, Kuniyal JC (2023) Pretreatment of lignocellulosic biomass: review of various physico-chemical and biological methods influencing the extent of biomass depolymerization. Int J Environ Sci Technol 4:1–18. https://doi.org/10.1007/s13762-023-04838-4

Cai J, Wang Y, Liu J, Zhang X, Li F (2022) Pretreatment enhanced structural disruption, enzymatic hydrolysis, fermentative hydrogen production from rice straw. Int J Hydrog Energy 47:11778–11786. https://doi.org/10.1016/j.ijhydene.2022.01.214

Chaudhary G, Chaudhary N, Saini S, Gupta Y, Vivekanand V, Panghal A (2023) Assessment of pretreatment strategies for valorization of lignocellulosic biomass: path forwarding towards lignocellulosic biorefinery. Waste Biomass Valori 17:1–36. https://doi.org/10.1007/s12649-023-02219-z

Dehghani M, Karimi K, Sadeghi M (2015) Pretreatment of rice straw for the improvement of biogas production. Energy Fuels 29:3770–3775. https://doi.org/10.1021/acs.energyfuels.5b00718

Du J, Qian Y, Xi Y, Lü X (2019) Hydrothermal and alkaline thermal pretreatment at mild temperature in solid state for physicochemical properties and biogas production from anaerobic digestion of rice straw. Renew Energy 139:261–267. https://doi.org/10.1016/j.renene.2019.01.097

Esmaeili Z, Mojoodi S, Bazarganipour M, Zilouei H (2023) Investigating rice straw-based solidacid catalyst to hydrolyze cellulosic materials for biohydrogen production using Enterobacteraerogenes. Clean Technol Environ Policy 5:1–14. https://doi.org/10.1007/s10098-023-02516-0

Fazzino F, Pedullà A, Calabrò PS (2023) Boosting the circularity of waste management: pretreated mature landfill leachate enhances the anaerobic digestion of market waste. Biofuel Res J 10(1):1764–1773

Hansen LD (2023) Thermodynamic method for analyzing and optimizing pretreatment/anaerobic digestion systems. Biofuel Res J 10(2):1816–1826

Kaur A, Kuhad RC (2019) Valorization of rice straw for ethanol production and lignin recovery using combined acid-alkali pretreatment. Bioenergy Res 12:570–582. https://doi.org/10.1007/s12155-019-09988-3

Kumar R, Sharma P, Rose PK, Sahoo PK, Bhattacharya P, Pandey A, Kumar M (2023a) Co-transport and deposition of fluoride using rice husk-derived biochar in saturated porous media: effect of solution chemistry and surface properties. Environ Technol Innov 30:103056. https://doi.org/10.1016/j.eti.2023.103056

Kumar R, Sharma P, Sharma PK, Rose PK, Singh RK, Kumar N, Sahoo PK, Maity JP, Ghosh A, Kumar M, Bhattacharya P (2023b) Rice husk biochar-A novel engineered bio-based material for transforming groundwater-mediated fluoride cycling in natural environments. J Environ Manag 343:118222. https://doi.org/10.1016/j.jenvman.2023.118222

Le B, Yang SH (2019) Production of prebiotic xylooligosaccharide from aqueous ammonia- pretreated rice straw by β- xylosidase of Weissella cibaria. J Appl Microbiol 126:1861–1868. https://doi.org/10.1111/jam.14255

Mirmohamadsadeghi S, Karimi K, Azarbaijani R, Yeganeh LP, Angelidaki I, Nizami AS, Bhat R, Dashora K, Vijay VK, Aghbashlo M, Gupta VK (2021) Pretreatment of lignocelluloses for enhanced biogas production: a review on influencing mechanisms and the importance of microbial diversity. Renew Sustain Energy Rev 135:110173. https://doi.org/10.1016/j.rser.2020.110173

Mothe S, Polisetty VR (2021) Review on anaerobic digestion of rice straw for biogasproduction. Environ Sci Pollut Res 28:24455–24469. https://doi.org/10.1007/s11356-020-08762-9

Naik GP, Poonia AK, Chaudhari PK (2022) Maximization of biogas by minimal microwave and alkaline pretreatment of rice straw. Biomass Convers Bior 1–14. https://doi.org/10.1007/s13399-022-03539-1

New EK, Tnah SK, Voon KS, Yong KJ, Procentese A, Shak KP, Subramonian W, Cheng CK, Wu TY (2022) The application of green solvent in a biorefinery using lignocellulosic biomass as a feedstock. J Environ Manag 307:114385. https://doi.org/10.1016/j.jenvman.2021.114385

Niu K, Chen P, Zhang X, Tan WS (2009) Enhanced enzymatic hydrolysis of rice straw pretreated by alkali assisted with photocatalysis technology. J Chem Technol Biotechnol: Int Res Process Environ Clean Technol 84(8):1240–1245. https://doi.org/10.1002/jctb.2185

Peng J, Abomohra A-F, Elsayed M, Zhang X, Fan Q, Ai P (2019) Compositional changes of rice straw fibers after pretreatment with diluted acetic acid: towards enhanced biomethane production. J Clean Prod 230:775–782. https://doi.org/10.1016/j.jclepro.2019.05.155

Rashid J, Bhatti TT, Hassan M, Barakat MA, Kumar R, Xu M (2023) Enhancement inanaerobic biogas conversion by visible light photocatalytic pretreatment of rice husk with indium vanadate decorated titanium dioxide nanocomposite. Fuel 346:128289. https://doi.org/10.1016/j.fuel.2023.128289

Restiawaty E, Culsum NT, Nishiyama N, Budhi YW (2022) Preparation, characterization, and surface modification of cellulose nanocrystal from lignocellulosic biomass for immobilized lipase. Fibers 10(4):33. https://doi.org/10.3390/fib10040033

Rosado MJ, Marques G, Rencoret J, Gutiérrez A, Del Río JC (2022) Chemical composition of lipophilic compounds from rice (Oryza sativa) straw: an attractive feedstock for obtaining valuable phytochemicals. Front Plant Sci 13:868319. https://doi.org/10.3389/fpls.2022.868319

Rose PK (2022) Bioconversion of agricultural residue into biofuel and high-value biochemicals: recent advancement. In: Zero waste biorefinery (pp 233–268). Singapore: Springer Nature Singapore. https://doi.org/10.1007/978-981-16-8682-5_9

Rose PK, Dhull SB, Kidwai MK (2022) Cultivation of wild mushrooms using lignocellulosic biomass-based residue as a substrate. In: Wild mushrooms (pp 493–520). CRC Press, Boca Raton, Florida, USA

Rose PK, Kumar R, Kumar R, Kumar M, Sharma P (2023a) Congo red dye adsorption onto cationic amino-modified walnut shell: characterization, RSM optimization, isotherms, kinetics, and mechanism studies. Groundw Sustain Dev 100931. https://doi.org/10.1016/j.gsd.2023.100931

Rose PK, Poonia V, Kumar R, Kataria N, Sharma P, Lamba J, Bhattacharya P (2023b) Congo red dye removal using modified banana leaves: adsorption equilibrium, kinetics, and reusability analysis. Groundw Sustain Dev 23:101005. https://doi.org/10.1016/j.gsd.2023.101005

Saba M, Khan A, Bibi A, Gul Z, Hasan F, Shah AA, Khan S (2022) Microbial pretreatment of chicken feather and its co-digestion with rice husk and green grocery waste for enhanced biogas production. Front Microbiol 13:792426. https://doi.org/10.3389/fmicb.2022.792426

Sabeeh M, Liaquat R, Maryam A (2020) Effect of alkaline and alkaline-photocatalytic pretreatment on characteristics and biogas production of rice straw. Biores Technol 309:123449. https://doi.org/10.1016/j.biortech.2020.123449

Sari LN, Prayitno H, Farhan M, Syaichurrozi I (2022) Biogas production from rice straw. World Chem Eng J 6(2):44–49. https://doi.org/10.48181/wcej.v6i2.17995

Li X, Liu Y, Hao J, Wang W (2018) Study of almond shell characteristics. Materials 11(9):1782. https://doi.org/10.3390/ma11091782

Singh G, Gupta MK, Chaurasiya S, Sharma VS, Pimenov DY (2021) Rice straw burning: a review on its global prevalence and the sustainable alternatives for its effective mitigation. Environ Sci Poll Res 28(25):32125–32155. https://doi.org/10.1007/s11356-021-14163-3

Soltanian S, Aghbashlo M, Almasi F, Hosseinzadeh-Bandbafha H, Nizami AS, Ok YS, Lam SS, Tabatabaei M (2020) A critical review of the effects of pretreatment methods on the exergetic aspects of lignocellulosic biofuels. Energy Convers Manag 212:112792. https://doi.org/10.1016/j.enconman.2020.112792

Sun S, Zhang Y, Yang Z, Liu C, Zuo X, Tang Y, Wan P, Liu Y, Li X, Coulon F, Hu Q (2022) Improving the biodegradability of rice straw by electrochemical pretreatment. Fuel 330:125701. https://doi.org/10.1016/j.fuel.2022.125701

Takano M, Hoshino K (2018) Bioethanol production from rice straw by simultaneous saccharification and fermentation with statistical optimized cellulase cocktail and fermenting fungus. Bioresources Bioprocess 5(1):1–2. https://doi.org/10.1186/s40643-018-0203-y

Xiao K, Li H, Liu L, Liu X, Lian Y (2023) Quantitative comparison of the delignification performance of lignocellulosic biomass pretreatment technologies for enzymatic saccharification. Environ Sci Poll Res 30(9):22929–22940. https://doi.org/10.1007/s11356-022-23817-9

Xin L, Guo Z, Xiao X, Peng C, Zeng P, Feng W, Xu W (2019) Feasibility of anaerobic digestion on the release of biogas and heavy metals from rice straw pretreated with sodium hydroxide. Environ Sci Poll Res 26:19434–19444. https://doi.org/10.1007/s11356-022-24704-z

Zhang W, Liu J, Wang Y, Sun J, Huang P, Chang K (2021) Effect of ultrasound on ionic liquid-hydrochloric acid pretreatment with rice straw. Biomass Conver Biore 11:1749–1757. https://doi.org/10.1007/s13399-019-00595-y

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Department of Environmental Science and Engineering, Guru Jambheshwar University of Science and Technology, Hisar, Haryana, 125001, India

Nisha Sethi, Neha Luhach, Anita Singh Kirrolia, Asha Gupta & Narsi Ram Bishnoi

Department of Food Science and Technology, Chaudhary Devi Lal University, Sirsa, Haryana, 125055, India

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Department of Energy and Environmental Sciences, Chaudhary Devi Lal University, Sirsa, Haryana, 125055, India

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All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Nisha Sethi, Neha Luhach and Anita Singh Kirroloa. Asha Gupta and Narsi Ram Bishnoi supervised the work. The first draft of the manuscript was written by Nisha Sethi, and all the authors commented on previous versions of the manuscript. Sanju Bala Dhull moderated the whole manuscript. Pawan Kumar Rose reviewed, edited and prepared the final draft for submission to the journal. All authors read and approved the final manuscript.

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Sethi, N., Luhach, N., Kirrolia, A.S. et al. Physicochemical characterization of rice straw before and after alkali-assist photocatalytic pretreatment: a comparative analysis. Environ Sci Pollut Res (2024). https://doi.org/10.1007/s11356-024-33647-6

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Received : 08 November 2023

Accepted : 07 May 2024

Published : 16 May 2024

DOI : https://doi.org/10.1007/s11356-024-33647-6

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