COSMOS-E: Guidance on conducting systematic reviews and meta-analyses of observational studies of etiology - PubMed (original) (raw)

COSMOS-E: Guidance on conducting systematic reviews and meta-analyses of observational studies of etiology

Olaf M Dekkers et al. PLoS Med. 2019.

Abstract

Background: To our knowledge, no publication providing overarching guidance on the conduct of systematic reviews of observational studies of etiology exists.

Methods and findings: Conducting Systematic Reviews and Meta-Analyses of Observational Studies of Etiology (COSMOS-E) provides guidance on all steps in systematic reviews of observational studies of etiology, from shaping the research question, defining exposure and outcomes, to assessing the risk of bias and statistical analysis. The writing group included researchers experienced in meta-analyses and observational studies of etiology. Standard peer-review was performed. While the structure of systematic reviews of observational studies on etiology may be similar to that for systematic reviews of randomised controlled trials, there are specific tasks within each component that differ. Examples include assessment for confounding, selection bias, and information bias. In systematic reviews of observational studies of etiology, combining studies in meta-analysis may lead to more precise estimates, but such greater precision does not automatically remedy potential bias. Thorough exploration of sources of heterogeneity is key when assessing the validity of estimates and causality.

Conclusion: As many reviews of observational studies on etiology are being performed, this document may provide researchers with guidance on how to conduct and analyse such reviews.

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Conflict of interest statement

I have read the journal's policy and the authors of this manuscript have the following competing interests: AGR has received lecture honoraria from Merck Serona and Janssen-Cilag, and independent research funding and lecture honoraria from Novo Nordisk and Sanofi Pasteur MSD. ME receives a stipend as a Specialty Consulting Editor for PLOS Medicine and serves on the journal's Editorial Board.

Figures

Fig 1

Fig 1. Flow chart of study selection.

From [15].

Fig 2

Fig 2. The causal structures of confounding and selection bias.

Fig 3

Fig 3. Illustration of the ecological fallacy.

Hypothetical example of aggregate and individual level CD4 cell count data at the start of ART. Adapted from [83]. ART, antiretroviral therapy.

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