Background: Serosorting, selecting sex partners of the same HIV status, may be associated with increased risk of sexually transmitted infection (STI). We examined the association between unprotected anal intercourse (UAI) with a seroconcordant partner and STIs among HIV-negative men who have sex with men (MSM) at an urban lesbian, gay, bisexual, and transgender STI clinic.
Methods: Subjects reported how they assessed their most recent sex partner's HIV status. Those who reported getting tested together or asking were classified as known concordant; those who determined their partner's serostatus based on appearance, age, or social aspects were classified as assumed concordant. Generalized estimating equations generated prevalence ratios for associations between seroconcordance and STIs.
Results: From May 2010 through October 2011, 961 HIV-negative MSM were screened for gonorrhea, chlamydia, and syphilis at 1110 visits. Sexually transmitted infection prevalence was 20.1%: 20.2% at visits with known seroconcordant UAI, 35.3% at visits with assumed seroconcordant UAI, 29.5% at visits where UAI with an unknown status partner was reported, 34.8% at visits with serodiscordant UAI, and 16.1% at visits with no reported UAI. Assumed serodiscordant UAI (adjusted prevalence ratio [aPR], 2.51; 95% confidence interval [CI], 1.79-3.51), unknown status partner (aPR, 1.76; 95% CI, 1.31-2.38), and serodiscordant UAI (aPR, 2.57; 95% CI, 1.76-3.75) were significant predictors of STI after controlling for age and race/ethnicity, STI history, alcohol use, substance use, and multiple sex partners. Known seroconcordant UAI was not associated with STI.
Conclusions: Assumed seroconcordant UAI was associated with increased STI prevalence, although known seroconcordant UAI was not. The risk associated with UAI with a partner of assumed seroconcordance should be emphasized for HIV-negative MSM.