The role of metformin in polycystic ovary syndrome: a systematic review

This meta-analysis evaluated the effectiveness of metforminin subfertile women with polycystic ovary syndrome (PCOS). Onlyrandomized trials investigating the effectiveness of metforminand PCOS definition consistent with the Rotterdam consensuscriteria, were eligible. Primary outcome was live birth rate.A literature search identified 27 trials. In therapy naïvewomen, we found no evidence of a difference in live birth ratewhen comparing metformin with clomifene citrate (CC) [relativerisks (RR) 0.73; 95% confidence interval (CI) 0.51–1.1]or comparing metformin plus CC with CC (RR 1.0; 95% CI 0.82–1.3).In CC-resistant women, metformin plus CC led to higher livebirth rates than CC alone (RR 6.4; 95% CI 1.2–35); metforminalso led to higher live birth rates than laparoscopic ovariandrilling (LOD) (RR 1.6; 95% CI 1.1–2.5). We found no evidencefor a positive effect of metformin on live birth when addedto LOD (RR 1.3; 95% CI 0.39–4.0) or FSH (RR 1.6; 95% CI0.95–2.9), or when co-administered in IVF (RR 1.5; 95%CI 0.92–2.5). In IVF, metformin led to fewer cases ofovarian hyperstimulation syndrome (OHSS) (RR 0.33; 95% CI 0.13–0.80).This meta-analysis demonstrates that CC is still first choicetherapy for women with therapy naïve PCOS. In CC-resistantwomen, the combination of CC plus metformin is the preferredtreatment option before starting with LOD or FSH. At present,there is no evidence of an improvement in live birth when addingmetformin to LOD or FSH. In IVF, metformin leads to a reducedrisk of OHSS.