Rectal and urethral STIs among young MSM: Prevalence, demographic and behavioral risk factors, and implications for HIV risk

Background: Young men who have sex with men (YMSM) have high and increasing rates of HIV infections.  STIs increase risk for HIV and can serve as a proxy biomedical outcome in HIV prevention studies. Chlamydia and gonorrhea are the two most common STIs among YMSM, but most available data comes from urethral testing and little is known about rectal STIs.

Method: HIV negative YMSM (18-29 years) were recruited online and through community-based HIV testing centers in three cities (Atlanta, Chicago, New York).  As part of their baseline assessment for an HIV prevention trial, participants completed self-report measures and self-collected urine and rectal swabs for Chlamydia/gonorrhea testing. To date we have enrolled 596 YMSM (target N = 750).

Results: Rectal STIs were more prevalent (12.9%) than urethral (3.9%). The sample was highly diverse, but there were no significant differences in STI rates. Younger YMSM had significantly higher rectal STI rates than older YMSM: 15.5% vs. 10.1% (p < .05).  Sexual positioning during condomless anal sex (CAS) in prior 3 months was strongly associated with rectal STIs (p < .01): no CAS 11.1%, insertive CAS only 7.6%, insertive and receptive CAS 11.5%, and receptive only CAS 22.1%. No association was found between use of lubricants and rectal STIs.

Discussion: Self-collection of rectal swabs with mail return for testing is feasible. Rectal Chlamydia/gonorrhea was more than 3 times more common than urethral infections, highlighting the public health significance of screening among YMSM and viability as a proxy biomedical endpoint for HIV prevention trials.