THE IMPACT OF BARIATRIC SURGERY COMPARED TO METFORMIN THERAPY ON PREGNANCY OUTCOMES IN PATIENTS WITH POLYCYSTIC OVARIAN SYNDROME
Catherine Chang*1, Jillian Poles2, Violeta Popov2,3
1Case Western Reserve University School of Medicine, Cleveland, MI; 2VA New York Harbor Healthcare System, Manhattan Campus, New York, NY; 3New York University School of Medicine, New York, NY
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. Weight loss is recommended as first-line treatment to improve clinical symptoms and pregnancy outcomes.
Aim
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
A systematic review of electronic databases was performed through August 2019, including MEDLINE and Embase. Dual extraction and quality assessment of studies was performed independently by two authors. Inclusion criteria were retrospective and prospective studies reporting 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. Primary outcome was pregnancy rate. Event rates (ER) with 95% confidence intervals (95% CI) were calculated with random effects analysis, as well as subgroup analyses and risk differences (RD). Heterogeneity assessed by the I2 statistic.
Results
The initial search identified 1,990 citations. Three randomized control trials, 3 prospective studies, and 4 retrospective studies with a total of 587 patients were included in the final analyses. The average follow-up time was 18.25 months (range 3-36 months). Rate of pregnancy after metformin therapy was 17.1% (95% CI 0.12-0.23, I2 = 0, 5 studies, n = 192). Rate of pregnancy after bariatric surgery was 34.9% (95% CI 0.20-0.53, I2 = 70.2%, 5 studies, n = 186), with p = 0.026 for the difference between the groups. Meta-regression by other independent covariates showed that within the bariatric surgery group, an Eastern country of origin was associated with an increased rate of pregnancy compared to a Western country of origin (R2 = 100).
In subgroup analysis, subjects on metformin had three times the likelihood of pregnancy compared to control (95% CI 1.29-7.37, p = 0.01). The metformin cohort had a 54% decrease in menstrual irregularity from baseline to follow-up (RD = 0.54, 95% CI 0.20-0.89, p = 0.002). The bariatric surgery cohort had a 92% decrease in menstrual irregularity (RD = 0.92, 95% CI 0.75-1.1, p < 0.001). Data reported on adverse events rates was insufficient.
Conclusion
Both metformin and bariatric surgery were associated with improved pregnancy rates among subjects with PCOS, although bariatric surgery was associated with more than double the pregnancy rates. Metformin had significantly higher rates of pregnancy compared to controls. Both bariatric surgery and metformin improved menstrual irregularity. More data on adverse events and long-term follow-up is needed to assess the efficacy of these therapies in patients with PCOS.
Figure 1. Forest plots of the rate of pregnancy after bariatric surgery (34%) versus rate of pregnancy after metformin therapy (17%). P value for the difference between the two interventions is 0.026.
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