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

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.

Systematic reviews and meta-analysis in nutrition research

“…For example, in a recent systematic review with AD meta-analysis on dietary patterns, bone mineral density and fracture risk, the PICOS framework included an open population (P), dietary patterns as the intervention (I), other dietary patterns as the comparison (C), bone mineral density, bone mineral content or fracture as the outcomes (O) and observational study designs (S) (68) . For observational studies dealing with aetiology, the population, exposure, control and outcomes framework has recently been suggested (32) . In addition, the type of study designs included should also be reported.…”

“…Since nutritionists tend to prefer a recommended intake that can be applied to various populations and groups with confidence, it is recommended that any such comparisons be conducted using a dose-response approach. This consists of modelling the association between the exposure and outcome to estimate the increase or decrease associated with one unit, or some other appropriate unit change, in exposure (32) . For example, using linear dose-response meta-analysis, Morze et al found no significant associations between a 10-g/d increase in chocolate intake and heart failure (relative risk = 0•99, 95 % CI 0•94, 1•04) as well as type 2 diabetes (relative risk = 0•94, 95 % CI 0•88, 1•01) (116) .…”

“…As previously mentioned, the original PRISMA statement provides guidance, including a checklist, for conducting and reporting a systematic review with AD meta-analysis (30) . In addition, recent guidance for conducting systematic reviews and meta-analyses of observational studies in aetiology is also available (32) and the Cochrane Handbook provides extensive information on the conduct of systematic reviews with AD meta-analysis (6) .…”

Optimizing Literature Search: TEMAS, A New Text-Mining Algorithm-Assisted Search Tool

“…Several communities have addressed the challenge of automated information retrieval in the literature [1][2][3] . Several methods are provided to perform systematic reviews such as PRISMA 4 , MOOSE 5 , or COSMO-E 6 . These methods are very effective when the research question is clearly formulated, however, they afford little guidance when the informational need of the researcher is less circumscribed, for instance looking for risk factors or predictive factors.…”

Chlamydia trachomatis and reproductive health: what can we learn from systematic reviews of observational studies?

“…They reviewed reports of 107 observational epidemiological studies (case–control, cohort or cross-sectional) published up to May 2018. Following good practice in systematic reviews of observational studies of aetiology,7 they defined the research question in a published protocol, stratified results by study design, provided unadjusted and confounder-adjusted estimates where available, assessed the risk of bias and examined reasons for heterogeneity. The 107 studies in this review reported on any of 12 outcomes of pregnancy or fertility.…”