An overview of systematic reviews found suboptimal reporting and methodological limitations of mediation studies investigating causal mechanisms

Cashin, Aidan G; Lee, Hopin; Lamb, Sarah E; Hopewell, Sally; Mansell, Gemma; Williams, Christopher M; Kamper, Steven J.; Henschke, Nicholas; McAuley, James H.

doi:10.1016/j.jclinepi.2019.03.005

Cited by 30 publications

(42 citation statements)

References 82 publications

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“…Our findings were in line with results of other MA reviews, which also outlined the heterogeneity in conducting and reporting MAs in practice [21e23]. However, while the previous reviews either assessed systematic reviews of MAs [21] or focused on studies using a particular approach [22] or a particular type of outcome [23], we here attempted to give a broader overview on the use of different approaches in different contexts.…”

Section: Discussionsupporting

confidence: 87%

The conduct and reporting of mediation analysis in recently published randomized controlled trials: results from a methodological systematic review

Superchi

Boutron

et al. 2020

Journal of Clinical Epidemiology

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Objectives: To describe the methodological characteristics of mediation analyses (MAs) reported in recent randomized controlled trials (RCTs) and to propose recommendations on the planning, conduct, and reporting of MAs in practice. Study Design and Setting: We conducted a systematic review by searching MEDLINE (January 1, 2017, to December 1, 2018) for all reports of RCTs or secondary analyses of previously published RCTs that reported a MA. Two reviewers independently screened the title, abstracts, and full texts of the identified reports and extracted the data from the 98 eligible studies. Results: MAs were nearly always (96%) based on a traditional mediation approach. Most studies did not report a sample size calculation for the MA (96%) or assess potential treatment-by-mediator interactions (96%). In 53% of studies, mediators and outcomes were simultaneously measured. In 57% of studies, mediator-mediator and mediator-outcome confounders were adjusted for in the analysis, although adjustment was often limited to few potential confounders. About 30% of studies discussed the assumptions underlying the MA. Conclusion: The conduct and reporting of MAs remained quite heterogeneous in practice. Future MAs could benefit from a consensusbased planning, conduct, and reporting guideline for MA.

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Section: Discussionsupporting

confidence: 87%

The conduct and reporting of mediation analysis in recently published randomized controlled trials: results from a methodological systematic review

Superchi

Boutron

et al. 2020

Journal of Clinical Epidemiology

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“…Secondly, we will extract specific information about the reporting quality of the methods and results of the mediation analysis. The assessment of reporting quality will be guided by the reporting of items identified from a scoping review of existing methodological and reporting guidance documents for mediation analyses, and from the findings of our recent overview of systematic reviews [1]. The assessment focuses on reporting items considered essential to appropriately interpret and reproduce a study that uses mediation analysis.…”

Section: Data Extractionmentioning

confidence: 99%

“…The effects of exposures and health interventions are presumed to work via biological or psychosocial mechanisms. In recent years, epidemiologists and clinical trialists have used mediation analysis to understand the causal mechanisms by which exposures and interventions exert their effects on health outcomes [1][2][3]. Mediation analysis is a quantitative method for evaluating causal mechanisms where the effect of interest is partitioned into "indirect effects" that work through the mechanism(s) of interest, and a "direct effect" that works through all other unspecified mechanisms [4].…”

Section: Introductionmentioning

confidence: 99%

“…The use of mediation analysis to understand the mechanisms of health interventions has been advocated by the US National Institute of Health (NIH), UK National Institute for Health Research (NIHR), and UK Medical Research Council (MRC) [1,2].…”

Section: Introductionmentioning

confidence: 99%

“…While the use of mediation analysis has become increasingly common in recent years, there is growing recognition that the reporting of studies that use mediation analysis to investigate causal mechanisms of healthcare interventions is heterogenous and often incomplete [1,[5][6][7][8][9][10][11]. A recent overview of reviews across 11 health care fields and 26 healthcare conditions showed that mediation studies often did not report effect sizes and precision estimates (14/ 54, 26%), the theoretical rationale for the mechanism being tested (7/54, 13%), and essential details of the analytical techniques (4/54, 7%) [1]. Reviews of primary mediation studies also show that the reporting of effect estimates and assumptions are varied across the literature [5] and that most mediation analyses of randomised trials did not report sample size calculations [11].…”

Section: Introductionmentioning

confidence: 99%

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Development of A Guideline for Reporting Mediation Analyses (AGReMA)

Cashin

McAuley

Lamb

et al. 2020

BMC Med Res Methodol

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Background: There are a growing number of studies using mediation analysis to understand the mechanisms of health interventions and exposures. Recent work has shown that the reporting of these studies is heterogenous and incomplete. This problem stifles clinical application, reproducibility, and evidence synthesis. This paper describes the processes and methods that will be used to develop a guideline for reporting studies of mediation analyses (AGReMA). Methods/design: AGReMA will be developed over five overlapping stages. Stage one will comprise a systematic review to examine relevant evidence on the quality of reporting in published studies that use mediation analysis. In the second stage we will consult a group of methodologists and applied researchers by using a Delphi process to identify items that should be considered for inclusion in AGReMA. The third stage will involve a consensus meeting to consolidate and prioritise key items to be included in AGReMA. The fourth stage will involve the production of AGReMA and an accompanying explanation and elaboration document. In the final stage we will disseminate the AGReMA statement via journals, conferences, and professional meetings across multiple disciplines. Discussion: The development and implementation of AGReMA will improve the standardization, transparency, and completeness in the reporting of studies that use mediation analysis to understand the mechanisms of health interventions and exposures.

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A Guideline for Reporting Mediation Analyses of Randomized Trials and Observational Studies

Lee

Cashin

Lamb

et al. 2021

JAMA

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266

136

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and the AGReMA group IMPORTANCE Mediation analyses of randomized trials and observational studies can generate evidence about the mechanisms by which interventions and exposures may influence health outcomes. Publications of mediation analyses are increasing, but the quality of their reporting is suboptimal.OBJECTIVE To develop international, consensus-based guidance for the reporting of mediation analyses of randomized trials and observational studies (A Guideline for Reporting Mediation Analyses; AGReMA). DESIGN, SETTING, AND PARTICIPANTSThe AGReMA statement was developed using the Enhancing Quality and Transparency of Health Research (EQUATOR) methodological framework for developing reporting guidelines. The guideline development process included (1) an overview of systematic reviews to assess the need for a reporting guideline; (2) review of systematic reviews of relevant evidence on reporting mediation analyses; (3) conducting a Delphi survey with panel members that included methodologists, statisticians, clinical trialists, epidemiologists, psychologists, applied clinical researchers, clinicians, implementation scientists, evidence synthesis experts, representatives from the EQUATOR Network, and journal editors (n = 19; June-November 2019); (4) having a consensus meeting (n = 15; April 28-29, 2020); and (5) conducting a 4-week external review and pilot test that included methodologists and potential users of AGReMA (n = 21; November 2020). RESULTSA previously reported overview of 54 systematic reviews of mediation studies demonstrated the need for a reporting guideline. Thirty-three potential reporting items were identified from 3 systematic reviews of mediation studies. Over 3 rounds, the Delphi panelists ranked the importance of these items, provided 60 qualitative comments for item refinement and prioritization, and suggested new items for consideration. All items were reviewed during a 2-day consensus meeting and participants agreed on a 25-item AGReMA statement for studies in which mediation analyses are the primary focus and a 9-item short-form AGReMA statement for studies in which mediation analyses are a secondary focus. These checklists were externally reviewed and pilot tested by 21 expert methodologists and potential users, which led to minor adjustments and consolidation of the checklists. CONCLUSIONS AND RELEVANCEThe AGReMA statement provides recommendations for reporting primary and secondary mediation analyses of randomized trials and observational studies. Improved reporting of studies that use mediation analyses could facilitate peer review and help produce publications that are complete, accurate, transparent, and reproducible.

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An overview of systematic reviews found suboptimal reporting and methodological limitations of mediation studies investigating causal mechanisms

Cited by 30 publications

References 82 publications

The conduct and reporting of mediation analysis in recently published randomized controlled trials: results from a methodological systematic review

The conduct and reporting of mediation analysis in recently published randomized controlled trials: results from a methodological systematic review

Development of A Guideline for Reporting Mediation Analyses (AGReMA)

A Guideline for Reporting Mediation Analyses of Randomized Trials and Observational Studies

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