Te there has been limited guidance on how to incorporate case series studies within systematic reviews assessing the effectiveness of an intervention, particularly with reference to assessing the methodological quality or risk of bias of these studies. Methods: An international working group was formed to review the methodological literature regarding case series as a form of evidence for inclusion in systematic reviews. The group then developed a critical appraisal tool based on the epidemiological literature relating to bias within these studies. This was then piloted, reviewed, and approved by JBI's international Scientific Committee. Results: The JBI critical appraisal tool for case series studies includes 10 questions addressing the internal validity and risk of bias of case series designs, particularly confounding, selection, and information bias, in addition to the importance of clear reporting. Conclusion: In certain situations, case series designs may represent the best available evidence to inform clinical practice. The JBI critical appraisal tool for case series offers systematic reviewers an approved method to assess the methodological quality of these studies....

JBI recently began the process of updating and revising its suite of critical appraisal tools to ensure that these tools remain compatible with recent developments within risk of bias science. Following a rigorous development process led by the JBI Effectiveness Methodology Group, this paper presents the revised critical appraisal tool for the assessment of risk of bias for randomized controlled trials. This paper also presents practical guidance on how the questions of this tool are to be interpreted and applied by systematic reviewers, while providing topical examples. We also discuss the major changes made to this tool compared to the previous version and justification for why these changes facilitate best-practice methodologies in this field.

Background: Single group data present unique challenges for synthesises of evidence. Proportional meta-analysis is becoming an increasingly common technique employed for the synthesis of single group data. Proportional meta-analysis shares many similarities with the conduct and reporting of comparative, or pairwise, meta-analysis. While robust and comprehensive methods exist detailing how researchers can conduct a meta-analysis that compares two (or more) groups against a common intervention, there is a scarcity of methodological guidance available to assist synthesisers of evidence in the conduct, interpretation, and importance of proportional meta-analysis in systematic reviews. Main body: This paper presents an overview targeted to synthesisers of evidence and systematic review authors that details the methods, importance, and interpretation of a proportional meta-analysis. We provide worked examples of how proportional meta-analyses have been conducted in research syntheses previously and consider the methods, statistical considerations, and presentation of this technique. Conclusion: This overview is designed to serve as practical guidance for synthesisers of evidence in the conduct of proportional meta-analyses.

Background: There is a notable lack of methodological and reporting guidance for systematic reviews of prevalence data. This information void has the potential to result in reviews that are inconsistent and inadequate to inform healthcare policy and decision making. The aim of this meta-epidemiological study is to describe the methodology of recently published prevalence systematic reviews. Methods: We searched MEDLINE (via PubMed) from February 2017 to February 2018 for systematic reviews of prevalence studies. We included systematic reviews assessing the prevalence of any clinical condition using patients as the unit of measurement and we summarized data related to reporting and methodology of the reviews. Results: A total of 235 systematic reviews of prevalence were analyzed. The median number of authors was 5 (interquartile range [IQR] 4–7), the median number of databases searched was 4 (3–6) and the median number of studies included in each review was 24 (IQR 15–41.5). Search strategies were presented for 68% of reviews. Forty five percent of reviews received external funding, and 24% did not provide funding information. Twenty three percent of included reviews had published or registered the systematic review protocol. Reporting guidelines were used in 72% of reviews. The quality of included studies was assessed in 80% of reviews. Nine reviews assessed the overall quality of evidence (4 using GRADE). Meta-analysis was conducted in 65% of reviews; 1% used Bayesian methods. Random effect meta-analysis was used in 94% of reviews; among them, 75% did not report the variance estimator used. Among the reviews with meta-analysis, 70% did not report how data was transformed; 59% percent conducted subgroup analysis, 38% conducted meta-regression and 2% estimated prediction interval; I² was estimated in 95% of analysis. Publication bias was examined in 48%. The most common software used was STATA (55%). Conclusions: Our results indicate that there are significant inconsistencies regarding how these reviews are conducted. Many of these differences arose in the assessment of methodological quality and the formal synthesis of comparable data. This variability indicates the need for clearer reporting standards and consensus on methodological guidance for systematic reviews of prevalence data.

Cohort studies are a robust analytical observational study design that explore the difference in outcomes between two cohorts, differentiated by their exposure status. Despite being observational in nature, they are often included in systematic reviews of effectiveness, particularly when randomized controlled trials are limited or not feasible. Like all studies included in a systematic review, cohort studies must undergo a critical appraisal process to assess the extent to which a study has considered potential bias in its design, conduct, or analysis. Critical appraisal tools facilitate this evaluation. This paper introduces the revised critical appraisal tool for cohort studies, completed by the JBI Effectiveness Methodology Group, who are currently revising the suite of JBI critical appraisal tools for quantitative study designs. The revised tool responds to updates in methodological guidance from the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) Working Group and reporting guidance from PRISMA 2020, providing a robust framework for evaluating risk of bias in a cohort study. Transparent and rigorous assessment using this tool will assist reviewers in understanding the validity and relevance of the results and conclusions drawn from a systematic review that includes cohort studies. This may contribute to better evidence-based decision-making in health care. This paper discusses the key changes made to the tool, outlines justifications for these changes, and provides practical guidance on how this tool should be interpreted and applied by systematic reviewers.