Extending letrozole treatment duration is effective in inducing ovulation in women with polycystic ovary syndrome and letrozole resistance.

OBJECTIVE:To evaluate whether extending letrozole (LE) treatment duration could induce ovulation in women with polycystic ovary syndrome (PCOS) who previously failed to ovulate after a 5-day regimen of 5 mg LE daily for at least 1 ovulation induction cycle, defined as "LE resistance". DESIGN:Retrospective cohort study. SETTING:Tertiary care academic medical center. PATIENT(S):A total of 69 women with PCOS and LE resistance were included. INTERVENTION(S):The duration of LE treatment was increased in a stepwise manner (named as "2-step extended LE regimen"): a 7-day regimen of 5 mg LE daily was prescribed in the first ovulation induction cycle, and if ovulation did not occur, a 10-day regimen was prescribed in the subsequent cycle. MAIN OUTCOME MEASURE(S):Ovulation rate was the primary outcome. Clinical pregnancy rate, live birth rate, spontaneous ovulation rate, and ovarian hyperstimulation syndrome rate were the secondary outcomes. RESULT(S):Of the 69 patients, 48 ovulated after the 7-day and 16 after the 10-day regimen. Overall, the cumulative ovulation rate reached 92.75% (64/69) after the 2-step extended LE regimen, with a cumulative clinical pregnancy rate of 31.88% (22/69) and a cumulative live birth rate of 24.63% (17/69). All patients ovulated spontaneously without exogenous trigger agents and none experienced ovarian hyperstimulation syndrome. CONCLUSION(S):Extending LE treatment duration is a feasible method for inducing ovulation in women with PCOS and LE resistance.