Factors associated with nonresponse to ovulation induction using letrozole among women with World Health Organization group II anovulation

Abstract

CONTEXT:Letrozole, a third generation aromatase inhibitor is gaining importance in ovulation induction. Some prefer to use it as a second line agent in women who fail to respond to clomifene citrate. However, our knowledge about the predictors of response to letrozole is limited.AIMS:The study was aimed at identifying the factors associated with letrozole resistance among women with World Health Organization (WHO) group II anovulation.SUBJECTS AND METHODS:Study was conducted at the infertility clinic at a tertiary care hospital in Sri Lanka. A case–control study design was used and included 50 subjects with WHO group II anovulation (25 clomifene responsive and 25 clomifene resistant). After a treatment cycle of letrozole, the factors were compared between the subjects who responded and those who failed to respond to treatment.RESULTS:Ovulation was achieved in 76% (n = 19) of subjects who had responded to clomifene previously and in 24% (n = 6) with clomifene resistance. The factors associated with letrozole resistance included the presence of hirsutism (odds ratio [OR]: 3.89; 95% confidence interval [CI]: 1.2–12.3) and clomifene resistance (OR: 10.03; 95% CI: 2.81–35.7). The early follicular phase mean (standard deviation) luteinizing hormone level was significantly higher among the nonresponders (9.75 [4.78] – 7.28 [2.3]; P = 0.02). Nonresponders showed significantly lower levels of oestradiol on the 5th and 9th days (28.50 [3.39] pg/mL vs. 7.49 [3.62] pg/mL; P = 0.0007 and 142.04 [76.22] pg/mL vs. 28.10 [12.8] pg/mL; P = 0.0001) of the menstrual cycle, respectively.CONCLUSIONS:The features associated with resistance to Letrozole at a dose of 2.5 mg show some overlap with those associated with clomifene resistance. However, some features do not show similar association. The effectiveness of letrozole at a dose of 2.5 mg in induction of ovulation among women with clomifene resistance is low and it does not seem to be a suitable treatment at a dose of 2.5 mg for this indication.

Effects of letrozole in combination with low-dose intramuscularinjection of human menopausal gonadotropin on ovulation and pregnancy of 156 patients with polycystic ovary syndrome

“…The small impact of LE on the estrogen/progesterone ratio is conducive to maturation of the endometrium and receptivity increase 19. In this study, in the cycle with ovulation induction, the LE group had slightly fewer ovulation cycles and mature follicles than those of the CC group.…”

Predictors for Response to Letrozole as an Ovulation Induction in Anovulatory Infertile Polycystic Ovarian Syndrome Women

“…Mahran, et al [14] , Imani, et al [15] ). In comparison, few researchers studied letrozole predictors to response (Palihawadana, et al [16] ). [17] ).…”