Ethnicity and the Prevalence of Polycystic Ovary Syndrome: The Eastern Siberia PCOS Epidemiology and Phenotype Study

CONTEXT: Previous studies have shown that the prevalence of polycystic ovary syndrome (PCOS) may vary according to race/ethnicity, although a few studies have assessed women of different ethnicities who live in similar geographic and socioeconomic conditions. OBJECTIVE: To determine the prevalence of PCOS in an unselected multiethnic population of premenopausal women. DESIGN: A multicenter prospective cross-sectional study. SETTINGS: The main regional employers of Irkutsk Region and the Buryat Republic, Russia. PARTICIPANTS: During 2016-2019, 1398 premenopausal women underwent a history and physical exam, pelvic ultrasound, and testing during a mandatory annual employment-related health assessment. MAIN OUTCOME MEASURES: PCOS prevalence, overall and by ethnicity in a large medically unbiased population, including Caucasian (White), Mongolic or Asian (Buryat), and mixed ethnicity individuals living in similar geographic and socioeconomic conditions for centuries. RESULTS: PCOS was diagnosed in 165/1134 (14.5%) women who had a complete evaluation for PCOS. Based on the probabilities for PCOS by clinical presentation observed in the cohort of women who had a complete evaluation, we also estimated the weight-adjusted prevalence of PCOS in 264 women with an incomplete evaluation: 46.2 or 17.5%. Consequently, the total prevalence of PCOS in the population was 15.1%, higher among Caucasians and women of mixed ethnicity compared to Asians (16.0% and 21.8% vs 10.8%, Pz < .05). CONCLUSION: We observed a 15.1% prevalence of PCOS in our medically unbiased population of premenopausal women. In this population of Siberian premenopausal women of Caucasian, Asian, and mixed ethnicity living in similar geographic and socioeconomic conditions, the prevalence was higher in Caucasian or mixed than Asian women. These data highlight the need to assess carefully ethnic-dependent differences in the frequency and clinical manifestation of PCOS.