Small number of trials in meta-analyses

This problem is not addressed in any checklist or guideline. Meta-analyses in systematic reviews may often only include very few studies and if these are at high risk of bias or are heterogenous then they may produce misleading or spurious treatment effect estimates.

Articles that support this problem:

Systematic Reviews of Anesthesiologic Interventions Reported as Statistically Significant: Problems with Power, Precision, and Type 1 Error Protection

2015 : Anesthesia & analgesia

Reporting bias in the literature on the associations of health-related behaviors and statins with cardiovascular disease and all-cause mortality

2018 : Plos biology

Characteristics of meta-analyses and their component studies in the Cochrane Database of Systematic Reviews: a cross-sectional, descriptive analysis

2011 : Bmc medical research methodology

False-positive findings in Cochrane meta-analyses with and without application of trial sequential analysis: an empirical review

2016 : Bmj open

The knowledge system underpinning healthcare is not fit for purpose and must change

2015 : Bmj: british medical journal

Many meta-analyses of rare events in the Cochrane Database of Systematic Reviews were underpowered

2021 : Journal of clinical epidemiology