The difference between HIV and syphilis prevalence and incidence cases: results from a cohort study in Nanjing, China, 2008-2010

Int J STD AIDS. 2015 Aug;26(9):648-55. doi: 10.1177/0956462414550170. Epub 2014 Sep 23.


The available estimates of incidence and prevalence of syphilis among men who have sex with men (MSM) in Mainland China are high. We used respondent-driven sampling to recruit MSM in the study population. The participants were followed up to monitor the incidence and change of risk behaviours. A face-to-face interview was used to collect information about high-risk behaviours, demographics and recreational drug use. To test the difference between prevalent and incident cases, two nested matched case-control studies were carried out. The cases were the HIV or syphilis positives found at baseline and during follow-up. We used density sampling to sample six controls for each case. Our results indicate that compared to incident cases, prevalent cases had a higher proportion of reported unprotected anal intercourse for both HIV and syphilis. Regression analysis indicated that unprotected anal intercourse was the main risk factor among HIV-prevalent cases but not in HIV-incident cases. These differences could possibly be explained by the implementation of the risk reduction interventions. Syphilis was not a risk factor for HIV-prevalent cases but was highly associated with HIV-incident cases. Tailored interventions addressing unprotected anal intercourse and other risk factors can help to reduce the prevalence and incidence of HIV and syphilis.

Keywords: AIDS; Asia; HIV; MSM; epidemiology; incidence; location; men who have sex with men; risk factors; sexual behaviour; sexually transmitted infection; viral disease.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Case-Control Studies
  • China / epidemiology
  • Cohort Studies
  • Follow-Up Studies
  • HIV Infections / epidemiology*
  • Homosexuality, Male / statistics & numerical data*
  • Humans
  • Incidence
  • Male
  • Middle Aged
  • Prevalence
  • Regression Analysis
  • Risk Factors
  • Risk-Taking
  • Sexual Partners
  • Substance-Related Disorders / epidemiology
  • Syphilis / epidemiology*
  • Unsafe Sex / statistics & numerical data*