Metformin versus oral contraceptive pill in polycystic ovary syndrome: a Cochrane review

BACKGROUND: The object of this review was to compare metformin versus oral contraceptive pill (OCP) treatment in polycystic ovary syndrome. METHODS: A systematic review and meta-analysis employing the principles of the Cochrane Menstrual Disorders and Subfertility Group was undertaken. RESULTS: Four randomized controlled trials (RCTs) (104 subjects) were included. Limited data demonstrated no evidence of a difference in effect between metformin and the OCP on hirsutism, acne or development of type 2 diabetes mellitus. There were no trials assessing diagnosis of cardiovascular disease or endometrial cancer. Metformin, in comparison with the OCP, was less effective in improving menstrual pattern [Peto odds ratio (OR) 0.08, 95% confidence interval (CI) 0.01-0.45) and in reducing the serum total testosterone level weighted mean difference (WMD) 0.54, 95% CI 0.22-0.86] but more effective in reducing fasting insulin (WMD -3.46, 95% CI - 5.39 to -1.52) and not increasing fasting triglyceride (WMD -0.48, 95% CI - 0.86 to -0.09) levels. Limited data demonstrated no evidence of a difference in effect between the two therapies on reducing fasting glucose or total cholesterol levels and severe adverse events. CONCLUSIONS: The limited RCT evidence to date does not show adverse metabolic risk with the use of the OCP compared with metformin. Further long-term RCTs are required.