Comparison of efficacy of aromatase inhibitor and clomiphene citrate in induction of ovulation in polycystic ovarian syndrome

Objective: To compare the effectiveness of letrozole and clomiphene citrate (CC) in induction of ovulation in polycystic ovary syndrome (PCOS). Design: Prospective, randomized, not blinded, controlled trial. Setting: A tertiary level infertility care center. Patient(s): Sixty-four anovulatory patients with PCOS, who failed to ovulate when taking 100 mg/day CC in previous cycles. Intervention(s): Patients were randomly divided into two groups by lottery and treated with either 7.5 mg/day letrozole (an aromatase inhibitor) or 150 mg/day CC for 5 days starting from day 3 of the menstrual cycle. Main Outcome Measure(s): occurrence of ovulation, endometrial thickness, and pregnancy rate (PR). Result(s): Twenty (62.5%) patients from the letrozole group and 12 (37.50%) patients from the CC group ovulated during the observation period. Mean serum E-2 level was 817.75 pg/mL and 448.03 pg/mL in the CC and letrozole groups, respectively, on the day of hCG administration. The mean endometrial thickness on the day of hCG administration was 9.03 mm and 10.37 mm in the CC and letrozole groups, respectively. The mean D21 serum P was 13.09 ng/mL and 19.09 ng/mL in the CC and letrozole groups, respectively. Thirteen patients from the letrozole group (40.63%) and six patients from the CC group (18.75%) became pregnant. Conclusion(S): Letrozole has better ovulation and PR in comparison to CC in patients with PCOS. (Fertil Steril (R) 2009;92:853-7. (C)2009 by American Society for Reproductive Medicine.)