HIV incidence among men with and those without sexually transmitted rectal infections: estimates from matching against an HIV case registry.

Background: Sexually transmitted bacterial rectal infections are objective markers of HIV risk behavior. Quantifying HIV risk among men who have sex with men (MSM) who have had these infections can inform prevention efforts. We measured HIV risk among MSM who have and those who have not been diagnosed with rectal Chlamydia trachomatis (CT) and/or rectal Neisseria gonorrhoeae (GC).

Methods: HIV incidence among a cohort of 276 HIV-negative MSM diagnosed with rectal CT and/or GC in New York City sexually transmitted disease (STD) clinics was compared to HIV incidence among HIV-negative MSM without these infections. Matches against the citywide HIV/AIDS registry identified HIV diagnoses from STD clinics, and by other providers. Cox proportional hazards models were used to explore factors associated with HIV acquisition among MSM with rectal infections.

Results: HIV-negative MSM with rectal infections (>70% of which were asymptomatic) contributed 464.7 person-years of follow-up. Among them, 31 (11.2%) were diagnosed with HIV, of whom 14 (45%) were diagnosed by non-STD clinic providers. The annual HIV incidence was significantly higher among MSM with rectal infections (6.67%; 95% confidence interval [CI], 4.61%-9.35%) than among MSM without rectal infections (2.53%; 95% CI, 1.31%-4.42%). Black race (hazard ratio, 4.98; 95% CI, 1.75-14.17) was associated with incident HIV among MSM with rectal CT/GC.

Conclusions: One in 15 MSM with rectal infections was diagnosed with HIV within a year, a higher risk than for MSM without rectal infections. Such data have implications for screening for rectal STD, and may be useful for targeting populations for risk-reduction counseling and other HIV prevention strategies, such as preexposure prophylaxis.