The Impact of Bariatric Surgery Compared to Metformin Therapy on Pregnancy Outcomes in Patients with Polycystic Ovarian Syndrome: a Systematic Review and Meta-analysis

Background Polycystic ovarian syndrome (PCOS) is a leading cause of infertility among women of reproductive age. The interplay between hyperinsulinemia and obesity results in many of the reproductive and hormonal changes seen in PCOS including abnormal menses, infertility, and pregnancy loss. While bariatric surgery has been found to be an effective treatment strategy for morbid obesity, its role in the management of PCOS-related infertility compared to standard therapy (metformin) is less clear. Aims To assess the impact of bariatric surgery on pregnancy outcomes in women with PCOS compared to metformin therapy in a systematic review and meta-analysis. Methods MEDLINE, EMBASE, PubMed, and Google Scholar were searched from inception to August 2019. Studies that reported quantitative data on pregnancy outcomes on women of reproductive age with PCOS with at least a 3-month follow-up and a minimum of 5 or more sample size were included. The primary outcome was pregnancy rate, expressed as an event rate and 95% confidence interval (95% CI). Results Ten studies with a total of 587 patients were included in the final analyses (Metformin: 5 studies, n = 192; Bariatric surgery (BS): 5 studies (2 Roux-en-Y gastric bypass, 2 sleeve gastrectomy, 1 Roux-en-Y gastric bypass + sleeve gastrectomy), n = 186). The average time to follow-up was 18.25 months (range 3-36) with a shorter time to follow-up in the metformin group compared to the bariatric surgery group (Metformin: 11.2 vs BS: 24.5 months). While metformin increased the likelihood of pregnancy compared to placebo or non-surgical interventions (OR = 3.08, 95% CI 1.29-7.37, p = 0.01), the pregnancy rate after bariatric surgery was greater than metformin (34.9%, 95% CI 0.20-0.53 vs 17.1%, 95% CI 0.12-0.23, p = 0.026 for the difference). Additionally, there was a trend to a greater improvement in menstrual irregularity in the bariatric group compared to the metformin group with a reduction of 92% in the bariatric cohort compared to a reduction of 54% in the metformin cohort, but the data was limited. Conclusion Bariatric surgery appears to be a more effective treatment strategy for patients with PCOS and class 3 obesity compared to metformin alone. Women with PCOS and infertility should consider bariatric surgery for weight loss and improvement in pregnancy outcomes.