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Background: Condom serosorting, preferentially engaging in unprotected anal intercourse (UAI) with partners of the same HIV status, may provide limited protection against STIs and HIV.
Objectives: We sought to determine whether serosorting was associated with increased prevalence of bacterial STIs among HIV-negative MSM seeking STI testing at an urban LGBT STI clinic.
Methods: Data were collected from routine surveillance sources and enhanced behavioral assessments. Generalized estimating equations were used to generate odds ratios for associations between serosorting behaviors and STIs.
Results: May 2010-August 2011, 846 HIV-negative MSM were screened for gonorrhea, chlamydia, and syphilis at 912 visits. Men were median age 35, 75% NH-White, 7% NH-Black, 11% Hispanic, and 7% other race/ethnicity. 77% had ≥ 2 partners in the past 90 days; 62% reported anonymous partners in the past year; 59% had STI history; and alcohol (85%) and substance use (42%) were common. 60% had not been tested for HIV in the past 6 months. At last sexual encounter, 21% reported seroconcordant UAI (serosorting); 17% reported serodiscordant UAI; and 60% reported no UAI. Bacterial STI prevalence was 18.5% overall: 22% among serosorters; 27% among men reporting serodiscordant UAI; and 15% among those reporting no UAI. In multivariable regression, controlling for total sex partners (OR 1.7; 95% CI 1.0-2.7), alcohol (OR 1.8; 95% CI 1.0-3.1), ecstasy or methamphetamine use (OR 2.0; 95% CI 1.0-3.7), and STI history (OR 1.7; 95% CI 1.1-2.4), both serosorting (OR 1.7; 95% CI 1.1-2.7) and serodiscordant UAI (OR 2.2; 95% CI 1.4-3.4) were associated with an increased odds of STI diagnosis compared to no UAI.
Conclusions: Serosorting was associated with increased odds of bacterial STI diagnosis among high-risk HIV-negative MSM.
Implications for Programs, Policy, and Research: While some men engage in serosorting to reduce risk of HIV, this may lead to increased risk of STI.