The Effectiveness of Metformin in Women with Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Context: Polycystic ovary syndrome (PCOS) is one of the commonest endocrine disorders affecting women of reproductive age and metformin is widely used for manging this condition. Aim: To review the available literature on the effectiveness of metformin in women with PCOS. Data source: We searched PubMed, MEDLINE, Scopus, Embase, Cochrane library and the Web of Science in April 2020 and updated the search in PubMed in March 2021.Data synthesis: Two reviewers selected eligible studies and extracted data, and the review is reported according to the 2020 Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). Results:  In 24 eligible randomised controlled trials (RCTs), metformin has significantly reduced body weight by 3.13 kgs (95% CI: -5.33, -0.93), body mass index (BMI) by 0.82 kg/m² (95% CI: -1.22, -0.41), fasting blood glucose (standardised mean difference (SMD): -0.23; 95% CI: -0.40, -0.06), low density lipoprotein cholesterol (LDL-C) (SMD: -0.41; 95% CI: -0.85, 0.03), total testosterone (SMD: -0.33; 95% CI: -0.49, -0.17), androstadiene (SMD: -0.45; 95% CI: -0.70, -0.20), 17-hydroxyprogesterone (17-OHP)(SMD: -0.58; 95%CI: -1.16, 0.00) and increased clinical pregnancy rate (odd ratio (OR): 3.00; 95%CI: 1.95-4.59) compared to placebo.  Conclusion: Metformin was effective in reducing weight, BMI, total testosterone, androstenedione,  17-OHP, LDL-C, fasting blood glucose and increase rate of pregnancy in women with PCOS. Registration Details: PROSPERO registration No: CRD42020178783. Funding Statement: This systematic review was completed as part of a self-funded PhD project for MA, and no external fund was received. Declaration of Interests: None to declare.