AI Insight
This viewpoint article examines the credibility and reliability of meta-analyses, which are statistical syntheses that combine results from multiple existing studies rather than collecting new primary data. The authors note that while over 400,000 meta-analyses have been published between 1980 and 2025, their quality and trustworthiness vary considerably. Some meta-analyses have significantly influenced clinical practice and health policy, while others have produced misleading conclusions or unwarranted certainty.
Why it matters
Meta-analyses are increasingly used to guide medical decision-making and health policy, making it critical for clinicians and policymakers to distinguish reliable syntheses from flawed ones. Understanding what makes a meta-analysis credible helps prevent the adoption of ineffective or harmful interventions based on poor-quality evidence synthesis.
Understand the Science
Meta-analysis, from Greek μετά (meta, after) and ἀνά-λυσις (ana-lysis, breaking up), refers to the analysis of analyses. Meta-analyses address what existing studies collectively allow to be inferred, rather than answering a primary research question. The use of meta-analysis has expanded rapidly, with more than 400 000 meta-analyses indexed in PubMed between 1980 and 2025 (appendix p 9). Yet the trustworthiness of meta-analyses varies widely. Some have reshaped clinical practice and policy; others have added noise or conveyed false certainty.