Decreasing age at first anal intercourse among men who have sex with men in China: a multicentre cross-sectional survey

Introduction: Literature on the age at first anal intercourse (AFAI) among men who have sex with men (MSM) is limited. We aimed to elucidate the evolution of AFAI and the factors associated with early AFAI, based on a large sample of MSM in China. Methods: We collected information on the demographics and sexual behaviours of MSM from seven large cities in China from 2012 to 2013. Blood samples were collected for HIV serology. AFAI was calculated for MSM born in different time periods. Linear regression models were used to explore factors associated with younger AFAI. Results: A total of 4491 MSM (median age: 27 years, median AFAI: 21 years) were recruited. Median AFAI decreased steadily from 33 years of age among MSM born from 1940 to 1959 to 18 years of age among MSM born from 1990 to 1996. Factors significantly associated with younger AFAI included more recent birth cohort, being unmarried or living with a male partner, being a student or industry worker, the gender of the first partner being male, and using Rush or Ecstasy in the past six months (p for all