Use of an aromatase inhibitor in patients with polycystic ovary syndrome:: a prospective randomized trial

Objective: to compare the use of aromatase inhibitor (letrozole) with the use of clomiphene citrate (CC). Design: Prospective randomized study. Setting: An infertility clinic in a university hospital. Patient(s): Seventy-four consecutive infertile patients with polycystic ovary syndrome were recruited. Thirty eight patients were randomized to the letrozole group (99 cycles), and the remaining patients were recruited to the CC group (95 cycles). Intervention(s): The aromatase inhibitor letrozole cycle and in 74.7% (71/95) of CC cycles. The median (minimum-maximum) number of follicles sized > 15mm in diameter on the day of hCG administration were 1 (0-4) and 1 (0-5) in the letrozole and CC groups, respectively. On the day of hCG administration, median serum E-2 concentration in the letrozole and CC groups were statistically different: 189 pg/mL (18-1,581 pg/mL) and 386 pg/mL (27-6,190 pg/mL), respectively. The median serum E-2 concentrations per follicle sized > 15 mm in diameter on the day of hCG also statistically differed between the letrozole and CC groups: 160 pg/mL (18-808 pg/mL) and 281 pg/mL (27-2,615 pg/mL), respectively. The median endometrial thickness on the day of hCG did not significantly differ between the CC and letrozole groups; it was 8 mm. Pregnancy was achieved in nine cycles (9.1%) of the letrozole group and in seven cycles (7.4%) of the CC group, which also was not a statistically significant difference. Conclusion(s): The aromatase inhibitor letrozole may be an acceptable alternative to CC as an ovulation induction drug in patients with PCOS.