Predictors of Letrezole success in ovulation induction among women with polycystic ovary syndrome resistant to clomiphene citrate

Abstract

Background: Clomiphen citrate is still the traditional therapy used for inducing ovulation in polycystic ovary syndrome. 20-25% of patients with this syndrome does not respond to clomiphen citrate and fail to develop follicles of desirable size. Letrozol, an aromatase inhibitor, is increasingly used for induction of ovulation in women in whom clomiphen citrate was unsuccessful.Methods: In a prospective study, during the period from October 2008 to the end of December 2009, in infertility clinic in Al-Yarmouk Teaching hospital, fifty one infertile women were diagnosed as having polycystic ovary syndrome according to the Rotterdam criteria; all patients had previously received clomiphene citrate and were diagnosed as having resistance to this drug. Those patients were assigned to receive an aromatase inhibitor, letrizole, in a dose of 2.5 mg, increased to 5 mg in subsequent cycles, given orally from the third day of a spontaneous bleeding or progesterone-induced withdrawal bleeding for 5 days. The primary outcome measures were number of growing and mature follicles and endometrial thickness. Secondary outcome measures were the occurrence of pregnancy and miscarriage.Results: With 51 patients and 122 cycles of letrezole therapy, we had 84 (69.2%) ovulatory cycle and 18 pregnancies (15.4%). This study has showed that the body mass index is significantly different between the two groups and the cut off point for it is equal to or more than 26 (sensitivity 60.71% and specificity 78.26%). The mean cycle day of human chorionic gonadotrophine (h CG) administration was 13.4±1.67.The mean number of mature follicles (more than 18 mm in size) on the day of h CG administration was 1.21(range 1-2) and the mean endometrial thickness on same day was 10.2±1.31mm.Letrezole was well tolerated with no reported side effectsConclusion: Induction of ovulation with letrezole in clomiphene citrate-resistant polycystic ovary syndrome patients is associated with limited number of mature follicles without adverse effect on endometrial thickness. The rates of ovulation and pregnancy are encouraging. One of notable finding is the association of high body mass index with high response rate to letrezole.Keyword: Aromatase inhibitors (letrezole), Polycystic Ovarian Syndrome