The PCOSACT trial (Legro et al., NEJM 2014) directly compared letrozole versus clomiphene for ovulation induction in PCOS. What was the primary outcome result?

• A Letrozole had significantly higher ovulation rates but equivalent live birth rates to clomiphene
• B Letrozole had significantly higher live birth rates (27.5% vs 19.1% per cycle) and cumulative live birth rates over 5 cycles ✓
• C Clomiphene had higher ovulation rates; letrozole had higher multiple pregnancy rates due to multi-follicular development
• D Both agents had equivalent live birth rates, but letrozole had fewer multi-fetal pregnancies

Explanation

The PCOSACT trial (626 anovulatory PCOS women, 5 cycles) showed letrozole had significantly higher cumulative live birth rates (27.5% vs 19.1% per person) and higher ovulation rates, with no difference in miscarriage rates. Multiple gestation rates were similarly low in both groups. This trial established letrozole as the preferred first-line agent for ovulation induction in PCOS, replacing clomiphene. Option D incorrectly states equivalence — the difference was statistically significant.

Reference: Shaw's Textbook of Gynaecology, 17th ed.

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