A comparison of letrozole regimens for ovulation induction in women with polycystic ovary syndrome

Objective: To determine the optimal letrozole regimen for ovulation induction (OI) in women with polycystic ovary syndrome (PCOS) Design: Retrospective cohort study. Setting: Single academic fertility clinic from 2015 -2022 Patient(s): 189 OI cycles in 52 patients with PCOS Intervention(s): Patients were prescribed one of four letrozole regimens (group 1:2.5mg for 5 days, group 2: 2.5mg for 10 days, group 3: 5mg for 5 days, and group 4: 5mg for 10 days). Main outcome measure(s):The primary outcome was ovulation, and secondary outcomes included multi-follicular development, and clinical pregnancy rate, which were analyzed with binary logistic regression.Kaplan-Meier cumulative response curves and a Cox proportional hazard regression model were used for time-dependent analyses.Results: Mean age was 30.9 years (standard deviation (SD) 3.6) and body mass index was 32.1 (SD 4.0).Group 2 (odds ratio (OR) 9.12, 95% confidence interval (CI) 1.92-43.25,P=0.005), group 3 (OR 3.40, 95% CI 1.57-7.37,P=0.002), and group 4 (OR 5.94, 95% CI 2.48-14.23,P<0.001) had improved ovulation rates after the starting regimen as compared to group 1. Cumulative ovulation rates exceeded 84% in all groups (P=NS), yet those who received 5mg and/or 10 days achieved ovulation significantly sooner (P<0.01).Multifollicular development was not increased in groups 2-4 as compared to group 1 (P=NS).Groups 2-4 also demonstrated improved time to pregnancy (P<0.01).