Prevalence of Polycystic Ovarian Syndrome, Phenotypes and their Ovulation Response to Sequential Letrozole Dose Escalation among Infertile Women at a Tertiary Care Centre in Southern India

BACKGROUND: Women with polycystic ovarian syndrome (PCOS) often have anovulatory infertility requiring ovulation induction with letrozole. AIMS: This study aimed to determine the prevalence and phenotypic categorisation of infertile PCOS women and to assess ovulatory response and pregnancy rates of PCOS phenotypes with sequential letrozole dose escalation. STUDY SETTING AND DESIGN: This was a prospective observational study. MATERIALS AND METHODS: One hundred seventy-five infertile PCOS women were enrolled. One hundred fifty-six women received ovulation induction as per the protocol with sequential letrozole dose escalation in each subsequent cycle (2.5 mg, 5 mg and 7.5 mg). Responses were assessed by ovulation and/or pregnancy. STATISTICAL ANALYSIS USED: Descriptive statistics were elaborated by means, medians, frequencies and percentages. Group comparisons and linear correlation between two continuous variables were done using appropriate statistical tests. RESULTS: Eighty-seven (49.7%) women were Phenotype A; 11 (6.3%) were Phenotype B; 20 (11.4%) were Phenotype C and 57 (32.6%) were Phenotype D in our study. After excluding the lost to follow up participants in each induction cycle, 33.3% (2.5 mg dose); 62.8% (5 mg dose) and 78.9% (7.5 mg dose) women responded to letrozole. A significant increase in ovulation to escalating letrozole doses was noted (Phenotype A: 35.1% to 2.5 mg, 53.7% to 5 mg and 72.7% to 7.5 mg; Phenotype B: 30% to 2.5 mg and 80% to 5 mg; Phenotype C: 35.3% to 2.5 mg and 87.5% to 5 mg and Phenotype D: 30.8% to 2.5 mg, 65.6% to 5 mg and 87.5% to 7.5 mg). Fifty-six of 156 (35.9%) infertile PCOS women achieved pregnancy; increase in pregnancy rates with escalated doses of letrozole was noted. CONCLUSION: All PCOS phenotypes show a similar response to escalating doses of letrozole. The role of phenotypic sub-categorisation for variable response to letrozole as an ovulation-inducing agent is uncertain.