Aromatase Inhibitors For Ovarian Stimulation In Subfertile Women With Polycystic Ovary Syndrome Summary Of A Cochrane Meta-Analysis

Background. Polycystic ovary syndrome (PCOS) is the most common cause of infrequent periods (oligomenorrhoea) and absence of periods (amenorrhoea), often leading to subfertlity. The aim of this metaanalysis was to compare the effectiveness and safety of aromatase inhibitors with other medical therapies for ovulation induction in subfertile women with PCOS. Methods. An extensive systematic literature search was done to identify relevant randomized controlled trials (RCTs). The primary outcomes were live birth and ovarian hyperstimulation syndrome (OHSS). Secondary endpoints were pregnancy rate, miscarriage rate, andmultiple pregnancy rate. Results. A total of 42 RCTs (7935 women) in which the aromatase inhibitor letrozole was used were included. In 25 RCTs, comparisons were also made to clomiphene citrate. Live birth rates were higher with letrozole compared to clomiphene citrate (odds ratio [OR] 1.68, 95% CI 1.42-1.99; 2954 participants; 13 studies; I2= 0%; number needed to treat for an additional beneficial outcome [NNTB]= 10; moderate-quality evidence). There is highquality evidence that OHSS rates are similar with letrozole and clomiphene citrate (0.5% in both arms: risk difference [RD] -0.00, 95% CI -0.01 to 0.00; 2536 participants; 12 studies; I2= 0%; high-quality evidence). There is evidence for a higher pregnancy rate in favor of letrozole (OR 1.56, 95% CI 1.37-1.78; 4629 participants; 25 studies; I2= 1%; NNTB= 10; moderate-quality evidence). There is little or no difference between treatment groups in the rate ofmiscarriage (OR 0.94, 95% CI 0.70-1.26; 1210 participants; 18 studies; I2= 0%; high-quality evidence) and multiple pregnancy rate (OR 0.69, 95% CI 0.41-1.16; 3579 participants; 17 studies; I2= 0%; highquality evidence). Conclusion. Compared to clomiphene citrate, letrozole shows a significantly increased rate of live births and pregnancies. The quality of evidence of the analysis is high to moderate. The incidence of OHSS was the same in both groups-