Meta-analysis of letrozole versus clomiphene citrate in polycystic ovary syndrome

The aim of this study was to systematically compare the clinical efficacy and safety of letrozole with clomiphene citrate for ovulation induction in women with polycystic ovary syndrome (PCOS). The Cochrane Central Register of Controlled Trials, PubMed, EMbase, CBMdisc and CNKI were searched for eligible randomized controlled trials (RCT) comparing letrozole with clomiphene citrate in PCOS patients. Two reviewers independently extracted information and evaluated methodological quality according to the Cochrane Handbook 5.0. Meta-analysis was performed with the fixed-effects model or random-effects model according to the heterogeneity. Six eligible RCT involving 841 patients were included. Letrozole was associated with a number of lower mature follicles per cycle (standardized mean difference (SMD) −1.41; 95% confidence intervales (CI) −1.54 to −1.28; P < 0.00001) compared with clomiphene citrate. There were no significant differences in pregnancy rate (relative risk (RR) 0.97; 95% CI 0.79 to 1.18), abortion rate (RR 1.38; 95% CI 0.48 to −3.96) and multiple pregnancy rate (RR 0.34; 95% CI 0.07 to −1.72) between the two groups. The evidence from ovulation rates was not enough to support either letrozole or clomiphene citrate. In conclusion, letrozole is as effective as clomiphene citrate for ovulation induction in patients with PCOS.Infertility is a primary clinical manifestation of polycystic ovary syndrome (PCOS). Ovulation induction is recognized as an essential treatment for patients with PCOS. The traditional ovulation-inducing agent clomiphene citrate and the new agent letrozole have both been widely used in recent years. Which is preferable? The aim of the current analysis was to answer this question by systematically collecting and evaluating available studies. The pooled analysis shows that letrozole treatment was associated with a lower number of mature follicles per cycle compared with clomiphene citrate. There were no significant differences in pregnancy, abortion and multiple pregnancy rates between the two groups. It is concluded that letrozole may be as effective as clomiphene citrate for ovulation induction in patients with PCOS.