Overview of reviews in child health: evidence synthesis and the knowledge base for a specific population

Prenatal exposure to ambient air pollutants and congenital heart defects: An umbrella review

BACKGROUND

Prenatal exposure to ambient air pollutants has been linked to congenital heart defects (CHD), but findings of existing systematic reviews have been mixed.

OBJECTIVE

To assess the epidemiological evidence on associations between prenatal exposure to ambient air pollutants and CHD subtypes, based on a systematic overview of reviews ("umbrella review").

METHODS

We conducted a systematic search for reviews assessing associations between prenatal exposure to criteria air pollutants and CHD. The risk of bias was evaluated using the Risk of Bias in Systematic Reviews (ROBIS) tool. The certainty of the systematic review findings was graded using the Navigation Guide methodology.

RESULTS

We identified eleven systematic reviews, including eight with meta-analyses, assessing in total 35 primary studies of prenatal exposure to criteria air pollutants and various CHD subtypes. The certainty of the findings of four meta-analyses indicating an increased risk for coarctation of the aorta associated with nitrogen dioxide exposure was rated as moderate. The certainty of findings indicating positive, inverse, or null associations for other pollutant-subtype combinations was rated as very low to low, based on low precision and high statistical heterogeneity of summary odds ratios (SOR), substantial inconsistencies between review findings, and methodological limitations of the systematic reviews.

DISCUSSION

The inconsistent findings and high statistical heterogeneity of many SOR of the included systematic reviews may partly be traced to differences in methodological approaches, and the risk of bias across included reviews (e.g., inclusion criteria, systematic search strategies, synthesis methods) and primary studies (e.g., exposure assessment, diagnostic criteria). Adherence to appropriate systematic review guidelines for environmental health research, as well as rigorous evaluation of risk of bias in primary studies, are essential for future risk assessments and policy-making. Still, our findings suggest that prenatal exposure to ambient air pollutants may increase risks for at least some CHD subtypes.

Cochrane overviews: how can we optimize their impact on evidence-based rehabilitation?

INTRODUCTION

Overviews (i.e. reviews of multiple systematic reviews) comprise a relatively novel methodology to systematically synthesize research findings. Overviews aim for a beneficial impact on clinical practice, but their methods and pathways to impact have so far not been mapped. The aim of this paper was to inform recommendations for optimizing impact on rehabilitation practice and research by mapping methods and pathways to impact in Cochrane overviews relevant to rehabilitation.

EVIDENCE ACQUISITION

We systematically searched and identified published Cochrane overviews (to June 2018) relevant to rehabilitation. We extracted data and compared overviews on key characteristics, methods of evidence synthesis, statements about impact, and access metrics. We explored one overview in detail regarding beneficiaries, activities and outputs, mapped potential pathways to impact, and, using an iterative process, refined this into a generic map. Through exploration of all synthesized data, we propose further recommendations for planning, conducting and reporting of future overviews in order to optimize impact on rehabilitation.

EVIDENCE SYNTHESIS

We identified seven Cochrane overviews relevant to rehabilitation. Their focus and methods varied, but they were broadly related to rehabilitation interventions for populations of people with diverse long-term conditions. Overviews also varied regarding their intended impact; only 4 overviews identified specific beneficiaries. All overviews included multiple tables and figures, but only one synthesized key findings into a single figure. For five overviews, the Altmetric Attention Score (a weighted count of attention that an output receives based on a range of online sources) was in the top 5% of all research outputs scored by Altmetric. The overview within our worked example had four key impact goals, each with different beneficiaries and required actions; this example led to a generic map of potential pathways to impact for other overviews.

CONCLUSIONS

Cochrane overviews have the potential to play a key role in knowledge translation and therefore to be useful in supporting evidence-based rehabilitation practice. However, current overviews relating to rehabilitation differ in methods, approaches and intended impact, and sometimes fall short of promoting easy access to key information for beneficiaries. Future Cochrane overviews should address topics of importance to key beneficiaries and clearly outline potential pathways to impact in order to have a potential beneficial impact on evidence-based rehabilitation and to improve rehabilitation outcomes.

Network meta-analysis of randomised trials of pharmacological, psychotherapeutic, exercise and collaborative care interventions for depressive symptoms in patients with coronary artery disease: hybrid systematic review of systematic reviews protocol

BACKGROUND

Depression is common in patients with coronary artery disease (CAD) and is associated with poorer outcomes and higher costs. Several randomised controlled trials (RCTs) targeting depression, of various modalities (including pharmacological, psychotherapeutic and other approaches), have been conducted and summarised in pairwise meta-analytic reviews. However, no study has considered the cumulative evidence within a network, which can provide valuable indirect comparisons and information about the relative efficacy of interventions. Therefore, we will adopt a review of review methodology to develop a network meta-analysis (NMA) of depression interventions for depression in CAD.

METHODS

We will search relevant databases from inception for systematic reviews of RCTs of depression treatments for people with CAD, supplementing this with comprehensive searches for recent or ongoing studies. We will extract data from and summarise characteristics of individual RCTs, including participants, study characteristics, outcome measures and adverse events. Cochrane risk of bias ratings will also be extracted or if not present will be conducted by the authors. RCTs that compare depression treatments (grouped as pharmacological, psychotherapeutic, combined pharmacological/psychotherapeutic, exercise, collaborative care) to placebo, usual care, waitlist control or attention controls, or directly in head-to-head comparisons, will be included. Primary outcomes will be the change in depressive symptoms (summarised with a standardised mean difference) and treatment acceptability (treatment discontinuation: % of people who withdrew). Secondary outcomes will include change in 6-month depression outcomes, health-related quality of life (HRQoL), mortality, cardiovascular morbidity, health services use and adverse events. Secondary analyses will form further networks with individual anti-depressants and psychotherapies. We will use frequentist, random effects multivariate network meta-analysis to synthesise the evidence for depression intervention and to achieve a ranking of treatments, using Stata. Rankograms and surface under the cumulative ranking curves will be used for treatment ranking. Local and global methods will evaluate consistency. GRADE will be used to assess evidence quality for primary outcomes.

DISCUSSION

The present review will address uncertainties about the evidence in terms of depression management in CAD and may allow for a ranking of treatments, including providing important information for future research efforts.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018108293.

A decision tool to help researchers make decisions about including systematic reviews in overviews of reviews of healthcare interventions

BACKGROUND

Overviews of reviews of healthcare interventions (overviews) integrate information from multiple systematic reviews (SRs) to provide a single synthesis of relevant evidence for decision-making. Overviews may identify multiple SRs that examine the same intervention for the same condition and include some, but not all, of the same primary studies. Different researchers use different approaches to manage these "overlapping SRs," but each approach has advantages and disadvantages. This study aimed to develop an evidence-based decision tool to help researchers make informed inclusion decisions when conducting overviews of healthcare interventions.

METHODS

We used a two-stage process to develop the decision tool. First, we conducted a multiple case study to obtain empirical evidence upon which the tool is based. We systematically conducted seven overviews five times each, making five different decisions about which SRs to include in the overviews, for a total of 35 overviews; we then examined the impact of the five inclusion decisions on the overviews' comprehensiveness and challenges, within and across the seven overview cases. Second, we used a structured, iterative process to transform the evidence obtained from the multiple case study into an empirically based decision tool with accompanying descriptive text.

RESULTS

The resulting decision tool contains four questions: (1) Do Cochrane SRs likely examine all relevant intervention comparisons and available data? (2) Do the Cochrane SRs overlap? (3) Do the non-Cochrane SRs overlap? (4) Are researchers prepared and able to avoid double-counting outcome data from overlapping SRs, by ensuring that each primary study's outcome data are extracted from overlapping SRs only once? Guidance is provided to help researchers answer each question, and empirical evidence is provided regarding the advantages, disadvantages, and potential trade-offs of the different inclusion decisions.

CONCLUSIONS

This evidence-based decision tool is designed to provide researchers with the knowledge and means to make informed inclusion decisions in overviews. The tool can provide practical guidance and support for overview authors by helping them consider questions that could affect the comprehensiveness and complexity of their overviews. We hope this tool will be a useful resource for researchers conducting overviews, and we welcome discussion, testing, and refinement of the proposed tool.

The impact of different inclusion decisions on the comprehensiveness and complexity of overviews of reviews of healthcare interventions

BACKGROUND

Overviews of reviews (overviews) compile information from multiple systematic reviews (SRs) to provide a single synthesis of relevant evidence for decision-making. Overviews may identify multiple SRs that examine the same intervention for the same condition and include some, but not all, of the same primary studies. There is currently limited guidance on whether and how to include these overlapping SRs in overviews. Our objectives were to assess how different inclusion decisions in overviews of healthcare interventions affect their comprehensiveness and results, and document challenges encountered when making different inclusion decisions in overviews.

METHODS

We used five inclusion decisions to conduct overviews across seven topic areas, resulting in 35 overviews. The inclusion decisions were (1) include all Cochrane and non-Cochrane SRs, (2) include only Cochrane SRs, or consider all Cochrane and non-Cochrane SRs but include only non-overlapping SRs, and in the case of overlapping SRs, select (3) the Cochrane SR, (4) the most recent SR (by publication or search date), or (5) the highest quality SR (assessed using AMSTAR). For each topic area and inclusion scenario, we documented the amount of outcome data lost and changed and the challenges involved.

RESULTS

When conducting overviews, including only Cochrane SRs, instead of all SRs, often led to loss/change of outcome data (median 31% of outcomes lost/changed; range 0-100%). Considering all Cochrane and non-Cochrane SRs but including only non-overlapping SRs and selecting the Cochrane SR for groups of overlapping SRs (instead of the most recent or highest quality SRs) allowed the most outcome data to be recaptured (median 42% of lost/changed outcome recaptured; range 28-86%). Across all inclusion scenarios, challenges were encountered when extracting data from overlapping SRs.

CONCLUSIONS

Overlapping SRs present a methodological challenge for overview authors. This study demonstrates that different inclusion decisions affect the comprehensiveness and results of overviews in different ways, depending in part on whether Cochrane SRs examine all intervention comparisons relevant to the overview. Study results were used to develop an evidence-based decision tool that provides practical guidance for overview authors.

Toward a comprehensive evidence map of overview of systematic review methods: paper 2-risk of bias assessment; synthesis, presentation and summary of the findings; and assessment of the certainty of the evidence

BACKGROUND

Overviews of systematic reviews (SRs) attempt to systematically retrieve and summarise the results of multiple systematic reviews. This is the second of two papers from a study aiming to develop a comprehensive evidence map of the methods used in overviews. Our objectives were to (a) develop a framework of methods for conducting, interpreting and reporting overviews (stage I)-the Methods for Overviews of Reviews (MOoR) framework-and (b) to create an evidence map by mapping studies that have evaluated overview methods to the framework (stage II). In the first paper, we reported findings for the four initial steps of an overview (specification of purpose, objectives and scope; eligibility criteria; search methods; data extraction). In this paper, we report the remaining steps: assessing risk of bias; synthesis, presentation and summary of the findings; and assessing certainty of the evidence arising from the overview.

METHODS

In stage I, we identified cross-sectional studies, guidance documents and commentaries that described methods proposed for, or used in, overviews. Based on these studies, we developed a framework of possible methods for overviews, categorised by the steps in conducting an overview. Multiple iterations of the framework were discussed and refined by all authors. In stage II, we identified studies evaluating methods and mapped these evaluations to the framework.

RESULTS

Forty-two stage I studies described methods relevant to one or more of the latter steps of an overview. Six studies evaluating methods were included in stage II. These mapped to steps involving (i) the assessment of risk of bias (RoB) in SRs (two SRs and three primary studies, all reporting evaluation of RoB tools) and (ii) the synthesis, presentation and summary of the findings (one primary study evaluating methods for measuring overlap).

CONCLUSION

Many methods have been described for use in the latter steps in conducting an overview; however, evaluation and guidance for applying these methods is sparse. The exception is RoB assessment, for which a multitude of tools exist-several with sufficient evaluation and guidance to recommend their use. Evaluation of other methods is required to provide a comprehensive evidence map.

An introduction to overviews of reviews: planning a relevant research question and objective for an overview

BACKGROUND

Overviews of systematic reviews are a relatively new approach to synthesising evidence, and research methods and associated guidance are developing. Within this paper we aim to help readers understand key issues which are essential to consider when taking the first steps in planning an overview. These issues relate to the development of clear, relevant research questions and objectives prior to the development of an overview protocol.

METHODS

Initial discussions and key concepts for this paper were formed during a workshop on overview methods at the 2016 UK Cochrane Symposium, at which all members of this author group presented work and contributed to wider discussions. Detailed descriptions of the various key features of overviews and their different objectives were created by the author group based upon current evidence (Higgins J, Green S. Cochrane Handbook Syst Rev Interv. 2011;4:5, Pollock M, et al. Sys Rev. 2016;5:190-205, Pollock A, et al. Cochrane overviews of reviews: exploring the methods and challenges. UK and Ireland: Cochrane Symposium; 2016, Pieper D, et al. Res Syn Meth. 2014;5:187-99, Lunny C, et al. Sys Rev. 2016;5:4-12, Hartling L, et al. Comparing multiple treatments: an introduction to overviews of reviews. In 23rd Cochrane Colloquium; 2015, Hartling L, et al. Plos One. 2012;7:1-8, Ballard M, Montgomery P. Res Syn Meth. 2017;8:92-108) and author experiences conducting overviews.

RESULTS

Within this paper we introduce different types of overviews and suggest common research questions addressed by these overviews. We briefly reflect on the key features and objectives of the example overviews discussed.

CONCLUSIONS

Clear decisions relating to the research questions and objectives are a fundamental first step during the initial planning stages for an overview. Key stakeholders should be involved at the earliest opportunity to ensure that the planned overview is relevant and meaningful to the potential end users of the overview. Following best practice in common with other forms of systematic evidence synthesis, an overview protocol should be published, ensuring transparency and reducing opportunities for introduction of bias in the conduct of the overview.

Toward a comprehensive evidence map of overview of systematic review methods: paper 1-purpose, eligibility, search and data extraction

BACKGROUND

Overviews of systematic reviews attempt to systematically retrieve and summarise the results of multiple systematic reviews. Methods for conducting, interpreting and reporting overviews are in their infancy. To date, there has been no evidence map of the methods used in overviews, thus making it difficult to determine the gaps and priorities for methods research. Our objectives were to develop and populate a comprehensive framework of methods for conducting, interpreting and reporting overviews (stage I) and to create an evidence map by mapping studies that have evaluated overview methods to the framework (stage II).

METHODS

We searched methods collections (e.g. Cochrane Methodology Register, Meth4ReSyn library, AHRQ Effective Health Care Program) to identify eligible studies for both stages of this research. In stage I, cross-sectional studies, guidance documents and commentaries that described methods proposed for, or used in, overviews were used to develop and populate the framework of methods. Drafts and multiple iterations of the framework were discussed and refined by all authors. In stage II, we identified and described studies evaluating overview methods and mapped these evaluations to the framework.

RESULTS

In this paper, we present results for the four initial steps of conducting an overview: (a) specification of the purpose, objectives and scope, (b) specification of the eligibility criteria, (c) search methods and (d) data extraction. Twenty-nine studies mentioned or described methods relevant to one or more of these steps. In the developed framework, identified methods and approaches were grouped according to the steps an overview author would need to undertake. Fifteen studies evaluated identified methods, all of which mapped to the search methods step. These studies either reported the development and evaluation of a new search filter to retrieve systematic reviews or compared the performance of multiple filters.

CONCLUSION

Gaps in the evaluation of methods were found for the majority of steps in the framework. More empirical studies are needed to evaluate the methods outlined and provide a comprehensive evidence map. The framework is useful for planning these evaluations and for planning methods required to deal with challenges that arise when conducting an overview.

Selecting and implementing overview methods: implications from five exemplar overviews

BACKGROUND

Overviews of systematic reviews are an increasingly popular method of evidence synthesis; there is a lack of clear guidance for completing overviews and a number of methodological challenges. At the UK Cochrane Symposium 2016, methodological challenges of five overviews were explored. Using data from these five overviews, practical implications to support methodological decision making of authors writing protocols for future overviews are proposed.

METHODS

Methods, and their justification, from the five exemplar overviews were tabulated and compared with areas of debate identified within current literature. Key methodological challenges and implications for development of overview protocols were generated and synthesised into a list, discussed and refined until there was consensus.

RESULTS

Methodological features of three Cochrane overviews, one overview of diagnostic test accuracy and one mixed methods overview have been summarised. Methods of selection of reviews and data extraction were similar. Either the AMSTAR or ROBIS tool was used to assess quality of included reviews. The GRADE approach was most commonly used to assess quality of evidence within the reviews. Eight key methodological challenges were identified from the exemplar overviews. There was good agreement between our findings and emerging areas of debate within a recent published synthesis. Implications for development of protocols for future overviews were identified.

CONCLUSIONS

Overviews are a relatively new methodological innovation, and there are currently substantial variations in the methodological approaches used within different overviews. There are considerable methodological challenges for which optimal solutions are not necessarily yet known. Lessons learnt from five exemplar overviews highlight a number of methodological decisions which may be beneficial to consider during the development of an overview protocol.

Risk of bias in overviews of reviews: a scoping review of methodological guidance and four-item checklist

OBJECTIVE

To assess the conditions under which employing an overview of systematic reviews is likely to lead to a high risk of bias.

STUDY DESIGN

To synthesise existing guidance concerning overview practice, a scoping review was conducted. Four electronic databases were searched with a pre-specified strategy (PROSPERO 2015:CRD42015027592) ending October 2015. Included studies needed to describe or develop overview methodology. Data were narratively synthesised to delineate areas highlighted as outstanding challenges or where methodological recommendations conflict.

RESULTS

Twenty-four papers met the inclusion criteria. There is emerging debate regarding overlapping systematic reviews; systematic review scope; quality of included research; updating; and synthesizing and reporting results. While three functions for overviews have been proposed-identify gaps, explore heterogeneity, summarize evidence-overviews cannot perform the first; are unlikely to achieve the second and third simultaneously; and can only perform the third under specific circumstances. Namely, when identified systematic reviews meet the following four conditions: (1) include primary trials that do not substantially overlap, (2) match overview scope, (3) are of high methodological quality, and (4) are up-to-date.

CONCLUSION

Considering the intended function of proposed overviews with the corresponding methodological conditions may improve the quality of this burgeoning publication type. Copyright © 2017 John Wiley & Sons, Ltd.

What guidance is available for researchers conducting overviews of reviews of healthcare interventions? A scoping review and qualitative metasummary

BACKGROUND

Overviews of reviews (overviews) compile data from multiple systematic reviews to provide a single synthesis of relevant evidence for decision-making. Despite their increasing popularity, there is limited methodological guidance available for researchers wishing to conduct overviews. The objective of this scoping review is to identify and collate all published and unpublished documents containing guidance for conducting overviews examining the efficacy, effectiveness, and/or safety of healthcare interventions. Our aims were to provide a map of existing guidance documents; identify similarities, differences, and gaps in the guidance contained within these documents; and identify common challenges involved in conducting overviews.

METHODS

We conducted an iterative and extensive search to ensure breadth and comprehensiveness of coverage. The search involved reference tracking, database and web searches (MEDLINE, EMBASE, DARE, Scopus, Cochrane Methods Studies Database, Google Scholar), handsearching of websites and conference proceedings, and contacting overview producers. Relevant guidance statements and challenges encountered were extracted, edited, grouped, abstracted, and presented using a qualitative metasummary approach.

RESULTS

We identified 52 guidance documents produced by 19 research groups. Relatively consistent guidance was available for the first stages of the overview process (deciding when and why to conduct an overview, specifying the scope, and searching for and including systematic reviews). In contrast, there was limited or conflicting guidance for the latter stages of the overview process (quality assessment of systematic reviews and their primary studies, collecting and analyzing data, and assessing quality of evidence), and many of the challenges identified were also related to these stages. An additional, overarching challenge identified was that overviews are limited by the methods, reporting, and coverage of their included systematic reviews.

CONCLUSIONS

This compilation of methodological guidance for conducting overviews of healthcare interventions will facilitate the production of future overviews and can help authors address key challenges they are likely to encounter. The results of this project have been used to identify areas where future methodological research is required to generate empirical evidence for overview methods. Additionally, these results have been used to update the chapter on overviews in the next edition of the Cochrane Handbook for Systematic Reviews of Interventions.

Retrieval of overviews of systematic reviews in MEDLINE was improved by the development of an objectively derived and validated search strategy

OBJECTIVES

Locating overviews of systematic reviews is difficult because of an absence of appropriate indexing terms and inconsistent terminology used to describe overviews. Our objective was to develop a validated search strategy to retrieve overviews in MEDLINE.

STUDY DESIGN AND SETTING

We derived a test set of overviews from the references of two method articles on overviews. Two population sets were used to identify discriminating terms, that is, terms that appear frequently in the test set but infrequently in two population sets of references found in MEDLINE. We used text mining to conduct a frequency analysis of terms appearing in the titles and abstracts. Candidate terms were combined and tested in MEDLINE in various permutations, and the performance of strategies measured using sensitivity and precision.

RESULTS

Two search strategies were developed: a sensitivity-maximizing strategy, achieving 93% sensitivity (95% confidence interval [CI]: 87, 96) and 7% precision (95% CI: 6, 8), and a sensitivity-and-precision-maximizing strategy, achieving 66% sensitivity (95% CI: 58, 74) and 21% precision (95% CI: 17, 25).

CONCLUSION

The developed search strategies enable users to more efficiently identify overviews of reviews compared to current strategies. Consistent language in describing overviews would aid in their identification, as would a specific MEDLINE Publication Type.

PREVENTING CHILD AND ADOLESCENT ANXIETY DISORDERS: OVERVIEW OF SYSTEMATIC REVIEWS

Overviews of systematic reviews (OSRs) provide rapid access to high quality, consolidated research evidence about prevention intervention options, supporting evidence-informed decision-making, and the identification of fruitful areas of new research. This OSR addressed three questions about prevention strategies for child and adolescent anxiety: (1) Does the intervention prevent anxiety diagnosis and/or reduce anxiety symptoms compared to passive controls? (2) Is the intervention equal to or more effective than active controls? (3) What is the evidence quality (EQ) for the intervention? Prespecified inclusion criteria identified systematic reviews and meta-analyses (2000-2014) with an AMSTAR quality score ≥ 3/5. EQ was rated using Oxford evidence levels EQ1 (highest) to EQ5 (lowest). Three reviews met inclusion criteria. One narrative systematic review concluded school-based interventions reduce anxiety symptoms. One meta-analysis pooled 65 randomized controlled trials (RCTs; any intervention) and reported a small, statistically significant reduction in anxiety symptoms and diagnosis incidence. Neither review provided pooled effect size estimates for specific intervention options defined by type (i.e., universal/selective/indicated), intervention content, or comparison group (i.e., passive/active control), thus precluding EQ ratings. One meta-analysis pooled trials of vigorous exercise and reported small, nonstatistically significant reductions in anxiety symptoms for comparisons against passive and active controls (EQ1). Better use of primary studies in meta-analyses, including program-specific pooled effect size estimates and network meta-analysis is needed to guide evidence-informed anxiety prevention program choices. RCTs of innovative community/primary care based interventions and web-based strategies can fill knowledge gaps.

An evaluation of harvest plots to display results of meta-analyses in overviews of reviews: a cross-sectional study

BACKGROUND

Harvest plots are used to graphically display evidence from complex and diverse studies or results. Overviews of reviews bring together evidence from two or more systematic reviews. Our objective was to determine the feasibility of using harvest plots to depict complex results of overviews of reviews.

METHODS

We conducted a survey of 279 members of Cochrane Child Health to determine their preferences for graphical display of data, and their understanding of data presented in the form of harvest plots. Preferences were rated on a scale of 0-100 (100 most preferred) and tabulated using descriptive statistics. Knowledge and accuracy were assessed by tabulating the number of correctly answered questions for harvest plots and traditional data summary tables; t-tests were used to compare responses between formats.

RESULTS

53 individuals from 7 countries completed the survey (19%): 60% were females; the majority had an MD (38%), PhD (47%), or equivalent. Respondents had published a median of 3 systematic reviews (inter-quartile range 1 to 8). There were few differences between harvest plots and tables in terms of being: well-suited to summarize and display results from meta-analysis (52 vs. 56); easy to understand (53 vs. 51); and, intuitive (49 vs. 44). Harvest plots were considered more aesthetically pleasing (56 vs. 44, p = 0.03). 40% felt the harvest plots could be used in conjunction with tables to display results from meta-analyses; additionally, 45% felt the harvest plots could be used with some improvement. There was no statistically significant difference in percentage of knowledge questions answered correctly for harvest plots compared with tables. When considering both types of data display, 21% of knowledge questions were answered incorrectly.

CONCLUSIONS

Neither harvest plots nor standard summary tables were ranked highly in terms of being easy to understand or intuitive, reflecting that neither format is ideal to summarize the results of meta-analyses in overviews of reviews. Responses to knowledge questions showed some misinterpretation of results of meta-analyses. Reviewers should ensure that messages are clearly articulated and summarized in the text to avoid misinterpretation.