Systematic reviews of medical evidence: the use of meta-analysis in obstetrics and gynecology.

OBJECTIVE

To review the technique of meta-analysis and its uses and limitations in obstetrics and gynecology.

DATA SOURCES

We reviewed four major journals in obstetrics and gynecology (American Journal of Obstetrics and Gynecology, Fertility and Sterility, Journal of Reproductive Medicine, and Obstetrics & Gynecology).

METHODS OF STUDY SELECTION

Journals were reviewed to determine frequency of meta-analysis as a method of systematic review in obstetrics and gynecology. We also summarized objectives and scientific guidelines for performing a meta-analysis.

TABULATION, INTEGRATION, AND RESULTS: Meta-analysis is used with increased frequency in obstetrics and gynecology as a way of systematically reviewing medical evidence. This technique is an attempt to improve on traditional methods of narrative review by an expert and as a framework for evidence-based medicine and developing practice guidelines. By combining data from replicate studies, a meta-analysis can increase statistical power, more precisely estimate the typical effect size of treatment or risk factor, and attempt to resolve controversies in the medical literature. Meta-analysis is a retrospective look at data already collected and is therefore subject to the biases of all retrospective studies.

CONCLUSIONS

The technique of meta-analysis requires all the scientific rigor of a randomized clinical trial with careful attention to study design, including a formal protocol for literature search strategies, quality assessment of candidate studies, specific inclusion and exclusion criteria, issues of sampling and publication bias, statistical tests of homogeneity, and sensitivity analysis.