Using The Respondent-driven-sampling To Recruit Men Who Have Sex With Men In Nanjing, China

Objective: Using the Respondent-Driven-Sampling (RDS) to recruit men who have sex with men(MSM), we examine the HIV / AIDS and syphilis prevalence, the demographic characteristics, the sexual behavior of MSM in Nanjing, Jiangsu Province, and provide evidence for future intervention. In addition, by evaluating the feasibility, diversity and equilibrium of the samples of RDS, we determine whether RDS can be used to recruit the hard-to-reach population and obtain a representative sample.Method: RDS was used to recruit MSM subjects. The blood was collected intravenously from 430 consented subjects for HIV, syphilis antibody measurements. Data were double entered with EpiData3.0. Before analysis, data were cleaned by logic check. Fitting Conditional Logistic Regression Model was applied for univariate and multivariate analysis. We applied Respondent Driven Sampling Analysis Tool (RDSAT) version 5.6 to calculate the population adjusted point estimation and 95% confidence intervals, the homophily. After individualized weights of selectedvariables were exported and combined with unweighed data with other variables, Fitting Conditional Logistic Regression Model was applied for univariate and multivariate analysis by using SPSS 16.0.Results:(1): Between May 5, 2008 to August 4, 430 MSM subjects were recruited in Nanjing, with the crude HIV and syphilis prevalence were 4.7% and 11.9%, while the adjusted HIV and syphilis prevalence were 6.6% (95% CI: 3.0, 10.4) and 12.6% (95% CI:8.1, 18.3) respectively, the prevalence of HIV and syphilis co-infection is 2.9% (95% CI : 0.3, 5.3); The estimated population size of MSM in Nanjing was 25,000, with the interval of 20,000 and 32,000; (2) compared with gay , those self-identified bisexualMSM have higher risk for HIV infection; (3) The MSM, who had infected with HIV, had the symptoms of STD, have higher risk for HIV infection; syphilis infection, UAI, the age of the first time of having sex with men were the risk factors of HIV infection. (4)UAI is associated with the marital status of being divorced or widowed, having sex with any one else except boy friend in past 6 months, being receptive during anal sex, being drunk before having sex with last male partner, having more than 2 different male sexual partners in the past 6 months. (5) both of the wave-based and week-based aaporaches can be used to evaluate the equilibrium of key indicators; RDS is an effective sampling method to recruit MSM.Conclusions: (1): MSM has high HIV and syphilis prevalence, which requires efforts in active prevention and education, including encouraging the MSM tested frequently, identifying more HIV-positive cases, therefore to prevent the HIV cases from spreading and slow down the epidemic; (2): by the analyzing feautres of the samples, which were recruited by RDS, we could find that RDS is an effective way to recruit hard-to-reach populations, and could get relatively representative samples.