Extended letrozole therapy for ovulation induction in clomiphene-resistant women with polycystic ovary syndrome: a novel protocol

ObjectiveTo evaluate the outcome of long letrozole therapy for induction of ovulation in patients with clomiphene-resistant polycystic ovary syndrome (PCOS).DesignProspective randomized controlled study.SettingUniversity teaching hospital and a private practice.Patient(s)The study comprised 218 patients with clomiphene-resistant PCOS.Intervention(s)Patients were randomly allocated to treatment with either long letrozole therapy (n = 108; 219 cycles) or short letrozole therapy (n = 110; 225 cycles).Main Outcome Measure(s)Number of growing and mature follicles, serum E2 (pg/mL), serum P (ng/mL), endometrial thickness, occurrence of pregnancy and miscarriage.Result(s)The number of ovulating patients was greater in the long letrozole group (65.7% vs. 61.8%), but without statistical differences. The total numbersof follicles during stimulation was significantly greater in the long letrozole group (6.7 ± 0.3 vs. 3.9 ± 0.4). The numbers of follicles ≥14 mm and ≥18 mm were significantly greater in the long letrozole group. There was no significant difference in the pretreatment endometrial thickness or endometrial thickness at the time of hCG administration between the two groups. Pregnancy occurred in 28 of 225 cycles in the short group (12.4%) and 38 of 219 cycles (17.4%) in the long letrozole group, and the difference was statistically significant.Conclusion(s)The long letrozole protocol (10 days) can produce more mature follicles and subsequently more pregnancies than the short letrozole thrapy (5 days).