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

Abstract

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)

A total of 189 OI cycles in 52 patients with PCOS

Intervention(s)

Patients were prescribed 1 of 4 letrozole regimens (group 1: 2.5 mg for 5 days, group 2: 2.5 mg for 10 days, group 3: 5 mg for 5 days, and group 4: 5 mg for 10 days).

Main outcome measure(s)

The primary outcome was ovulation, and secondary outcomes included multifollicular 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 kg/m² (SD, 4.0). Group 2 (odds ratio [OR], 9.12; 95% confidence interval [CI], 1.92–43.25), group 3 (OR, 3.40; 95% CI, 1.57-7.37), and group 4 (OR, 5.94; 95% CI, 2.48–14.23) had improved ovulation rates after the starting regimen as compared with group 1. Cumulative ovulation rates exceeded 84% in all groups, yet those who received 5 mg and/or 10 days achieved ovulation significantly sooner. Multifollicular development was not increased in groups 2–4 as compared with group 1. Groups 2–4 also demonstrated improved time to pregnancy.

Conclusions

Ovulation rates are improved when starting with letrozole at 5 mg and/or a 10-day extended course as compared with the frequently-used 2.5 mg for 5 days. This may shorten time to ovulation and pregnancy.