title: Distributions and trends in sexual behaviors and HIV incidence among men who have sex with men in China.
abstract: BACKGROUND
  HIV prevalence is increasing at a concerning rate among men who have sex with men (MSM) in China. Numerous studies have reported on levels of behaviors of Chinese MSM for different types of sexual partnerships, such as regular, non-commercial casual and commercial. This study aims to investigate the trends HIV incidence rates in relation to their risk sexual behaviors and partnership types among Chinese MSM.
  
  
  METHODS
  Through a comprehensive literature research from available English and Chinese literature databases, we collated relevant information of sexual behaviors of Chinese MSM. Further, with the utilization of a mathematical optimization approach, this study reconciles the distributions of sexual behavioral data over the last decade and infers the heterogeneous distributions of behavioral patterns among Chinese MSM. Distributions of high-risk behavioural indicators, including the number of sexual partners, number of sexual acts and condom usage in the past 6 months, are calibrated to available empirical data. Based on the resultant temporal trends in these distributions, the trends in HIV incidence rates associated with each type of partnership among MSM in China are also estimated.
  
  
  RESULTS
  A total of 55 qualified articles have been identified. An average MSM has approximately 0.96 (95% CI, 0.59-1.18) regular, 3.75 (1.72-6.25) casual and 1.61 (0.97-2.78) commercial partners over a 6 month period and 4.33 (2.81-6.46), 1.42 (0.62-3.08), 1.48 (0.79-3.30) sexual acts per partnership respectively, corresponding to a total of 11.87 (8.87-15.25) acts. Condom usage has increased significantly during 2002-2010, at annual increases of 3.58% (2.98-4.12%), 5.55% (4.55-6.54%), and 5.03% (4.19-5.74%) for regular, casual and commercial partners respectively. These behavioral data implies an increase in HIV incidence of approximately 3.3-fold, from 2.04 (1.96-2.12) to 7.02 (6.71-7.35) per 1000 person-years during the same period. The proportion of new infections attributed to regular partnerships increased from 34% to 40%, whereas infections attributed to commercial partnerships reduced from 29% to 23% during 2002-2010.
  
  
  CONCLUSIONS
  Regular partnerships are the main contributor of new HIV cases among MSM in China, public health intervention strategies are required to increase condom usage and HIV testing rates among regular partners to curb the growing trend HIV incidence.
authors: The Kirby Institute, University of New South Wales, Sydney, NSW 2052, Australia.
authors: Lei
authors: L
authors: Zhang
authors: Eric P F
authors: EP
authors: Chow
authors: David P
authors: DP
authors: Wilson
mesh_terms: D002681:China / Q000453:epidemiology; D015658:HIV Infections / Q000453:epidemiology*; D018451:Homosexuality, Male / Q000523:psychology*; D006801:Humans; D015994:Incidence; D008297:Male; D012309:Risk-Taking; D012725:Sexual Behavior / Q000706:statistics & numerical data*; D012747:Sexual Partners