4.2 (0.51-35.1) 13.2 (1.7-100.3)* 0 1 1 2.1(0.46-9.4) 5.7(1.2-27.0) * 11.0(1.4-88.2) * 2.8(0.3-22.3) 2.2(0.2-19.5) 1 Variable Original site JiangSu Province Guangxi Province GuangDong Province HaiNan Province Age (Years) 18-25 26-45 > 45 Ethnicity: Han Others Education Level Primary school equivalent or less Middle school High school College or higher Marital status Single Married Divorced/widowed Visiting FSW in the last 3 month and no condom use last time Yes 0.9(0.3-2.3) No 1 Have casual sex partnet other than FSW in the last 3 month and no condom use last time Yes No Homosexual/bisexual Yes No IDU in the last 6 months Yes No 2.8 (0.3-25.3) 12.3(1.5-97.4)* 0 1 3.9(2.9-5.2)** 1.4(1.0-2.0)* 2.5(1.7-3.6)** 1 1 1.6(1.2-2.0)** 2.3(1.7-3.1)** 1 0.3(0.2-0.7) ** 1.4(0.9-2.0) 1.5(1.1-2.0) 1.5(1.1-2.0) 1 1 1.4(1.1-1.7)* 1.1(0.6-2.0) 1.3(1.1-1.6) ** 1 1.2(1.0-1.6) * 1 Wang et al. BMC Public Health 2011, 11:955 http://www.biomedcentral.com/1471-2458/11/955 Table 4 Risk factors associated with HIV/STD among male STD clinic attendees Univariate OR(95%CI) HIV STD Multivariate AOR(95%CI) Univariate OR(95%CI) Multivariate AOR(95%CI) 13.1(2.9-59.4) ** 1 10.2 (1.3-81.6) * 1 16.9 (3.2-90.6) ** 1 19.1(2.1-176.1)* 1 CI = confidence interval; OR = odds ratio; AOR = adjusted odds ratio * P< 0.05 ** P < 0.01 Ministry of Health (MOH), five high HIV prevalence pro- vinces accounted for 80.5% of the total HIV/AIDS cases in the country [32]. Guangxi had a total of 20,604 reported HIV infections, ranking third highest among the provinces. In another study in Guangxi, the HIV preva- lence was similar (1.2%) to that of our study [33]. No HIV patients were found in Guangdong despite a moder- ate HIV epidemic in Guangdong, perhaps due to insuffi- cient patients recruitment in this province. No significant association was shown between HIV and sexual risk behaviors, perhaps due to a small HIV positive sample size. In our study, we found that investigation site, older age, lower education level, and unsafe sexual behavior with casual partners were factors that were independently associated with a STD. Notably, older participants had a higher risk for STD, which is different from previous reports which often showed a higher STD prevalence in younger participants. Due to limited economic capabil- ities, older men may tend to visit low-tier FSWs, where Page 6 of 8 3.8(2.8-5.3) ** 1.4(1.0-2.1) * 2.7(1.7-3.6)** 1 1 1.6(1.1-2.3)** 2.0(1.3-3.1)** 1.2(0.8-2.0) 1.6(1.2-2.3) ** 1.5(1.1-2.2) * 1 1.4(1.1-1.7) ** 1 1.3(1.0-1.7) * 1 1