Can meta-analyses be trusted?

Lancet. 1991 Nov 2;338(8775):1127-30. doi: 10.1016/0140-6736(91)91975-z.


The enthusiasm for meta-analyses (or overviews) expressed by their proponents is not always shared by the broader medical community. To encourage constructive debate, we adopt a critical perspective on the conduct and interpretation of meta-analysis. We focus particularly on some of the statistical issues, especially heterogeneity between studies, and also on the extrapolation of meta-analysis findings to clinical practice. We conclude that meta-analysis is not an exact statistical science that provides definitive simple answers to complex clinical problems. It is more appropriately viewed as a valuable objective descriptive technique, which often furnishes clear qualitative conclusions about broad treatment policies, but whose quantitative results have to be interpreted cautiously.

MeSH terms

  • Bias
  • Data Interpretation, Statistical*
  • Evaluation Studies as Topic
  • Female
  • Humans
  • Meta-Analysis as Topic*
  • Pre-Eclampsia / prevention & control
  • Pregnancy
  • Research Design
  • Statistics as Topic