Prevalence of polycystic ovary syndrome in women in China: a large community-based study

Study question: What is the prevalence of polycystic ovary syndrome (PCOS) in Han Chinese women from different communities?

Summary answer: The prevalence of PCOS in Chinese women aged 19-45 years is 5.6%.

What is known already: The prevalence of PCOS is reported to range from 5 to 10% but to the best of our knowledge the Han Chinese population has not been studied.

Study design, size, duration: A large-scale epidemiological study was carried out between October 2007 and September 2011 in 15 924 Han Chinese women of reproductive age (19-45 years) from the 10 provinces and municipalities in China.

Participants/materials, setting, methods: A total of 16 886 women from 152 cities and 112 villages were involved in the study. All study participants received a questionnaire and underwent a physical and transvaginal ultrasound examination. Blood samples were collected from a subsample of women (n = 3565) for analysis of metabolic markers and hormones. Based on the Rotterdam PCOS criteria, we assessed hyperandrogenism (H), chronic anovulation (O) and polycystic ovaries (P). Following diagnosis, women with PCOS were assigned to one of four different phenotypes. Finally, the prevalence and related risks of PCOS among Chinese women were estimated based on all the data sources.

Main results and the role of chance: A total of 16 886 women were initially involved in the study and 15 924 eligible participants then completed the study; the overall response rate was 94.3% (15 924/16 886). The prevalence of PCOS in the Chinese community population was 5.6% (894/15 924). Blood samples were analyzed from 833 of these women who were assigned to the four PCOS phenotypes as follows: 19% H + O, 37% H + P, 15% O + P and 29% H + O + P. Comparing the 833 women with PCOS to 2732 women without PCOS indicated that PCOS occurs in younger women (P < 0.05) and these women were prone not only to menstrual problems, hyperandrogenism, PCO and infertility but also metabolic syndrome (MS) and insulin resistance (IR). However, there was no significant difference in the rate of hypertension or hyperlipemia between the two groups. Obese patients with PCOS had a higher rate of MS (16 versus 48%), IR (7 versus 28%), hypertension (8 versus 30%) and hyperlipemia (48 versus 73%) compared with non-obese patients (all P < 0.05), respectively. The rates of metabolic complications in patients with PCOS increased with age.

Limitations, reasons for caution: Age and ethnic origin contribute to the differing manifestations of PCOS; therefore, sampling is one of the most important issues in epidemiological research into PCOS. Owing to the mobility of the Chinese population, the survey among resident populations caused a certain deviation in the age distribution.

Wider implications of the findings: The prevention and treatment of PCOS, particularly in those who are obese, are essential in Chinese women of reproductive age.