Anastrozole or letrozole for ovulation induction in clomiphene-resistant women with polycystic ovarian syndrome: a prospective randomized trial.Fertil Steril. 2008 May; 89(5):1209-12.FS
To compare the effects of letrozole (2.5 mg) and anastrozole (1 mg) meant for ovulation induction in clomiphene (CC)-resistant women with PCOS.
Prospective randomized trial.
University teaching hospital and private practice setting.
The study comprised a total of 220 infertile women (574 cycles) with CC-resistant PCOS.
Patients were randomized to treatment with 2.5 mg of letrozole daily (111 patients, 295 cycles) or 1 mg of anastrozole daily (109 patients, 279 cycles) for 5 days from day 3 of menses.
MAIN OUTCOME MEASURE(S)
Number of follicles, serum E(2), serum P, endometrial thickness, pregnancy rate (PR), and miscarriage rate.
The total number of follicles was significantly more in the anastrozole group (5.4 +/- 0.4 vs. 5.8 +/- 0.4). The number of follicles > or = 14 mm (3.1 +/- 0.3 vs. 2.7 +/- 0.2) and > or = 18 mm (2.3 +/- 0.1 vs. 3.1 +/- 0.2) were significantly higher in the anastrozole group. The endometrial thickness at the time of hCG administration was significantly more in the anastrozole group (9.1 +/- 0.2 vs. 10.2 +/- 0.7 mm). The duration to reach a dominant follicle was longer in the letrozole group (12.1 +/- 1.3 days vs. 8.8 +/- 1.9 days) but without statistical significant difference. Ovulation occurred in 183/295 cycles (62%) in the letrozole group and 177/279 cycles (63.4%) in the anastrozole group, whereas pregnancy occurred in 36/295 cycles (12.2%) in the letrozole group and 42/279 cycles (15.1%) in the anastrozole group and the differences were not statistically significant.
The results of this study did not show a significant difference in PR or miscarriage rate between anastrozole and letrozole when used for ovulation induction in women with CC-resistant PCOS.