HIV Incidence Among Men Who Have Sex With Men After Diagnosis With Sexually Transmitted Infections

Abstract

Background: Men who have sex with men (MSM) are at high risk for acquiring HIV infection after diagnosis with other sexually transmitted infections (STIs). Identifying the STIs associated with the greatest risk of subsequent HIV infection could help target prevention interventions, particularly preexposure prophylaxis (PrEP).

Methods: Using matched HIV and STI surveillance data from Washington State from January 1, 2007, to June 30, 2013, we calculated the incidence of new HIV diagnoses after different STI diagnoses among MSM. Men entered observation at the time of their first STI diagnosis during the study period and exited at HIV diagnosis or June 30, 2013. Cox proportional hazards regression was used to conduct a global comparison of rates.

Results: From January 1, 2007, to June 30, 2013, 6577 HIV-negative MSM were diagnosed as having 10,080 bacterial STIs at 8371 unique time points and followed for 17,419 person-years. Two hundred eighty (4.3%) men were subsequently diagnosed as having HIV infection for an overall incidence of 1.6 per 100 person-years (95% confidence interval, 1.4-1.8). The estimated incidence of HIV diagnoses among all MSM in the state was 0.4 per 100 person-years. Men who have sex with men were at the greatest risk for HIV diagnosis after being diagnosed as having rectal gonorrhea (HIV incidence, 4.1 per 100 person-years), followed by early syphilis (2.8), urethral gonorrhea (1.6), rectal chlamydial infection (1.6), pharyngeal gonorrhea (1.1), late syphilis (1.0), and urethral chlamydial infection (0.6; P < 0.0001 overall).

Conclusions: Men who have sex with men diagnosed as having rectal gonorrhea and early syphilis were at the greatest risk for being diagnosed as having HIV infection after STI diagnosis. These men should be prioritized for more intensive prevention interventions, including PrEP.

Figure 1. Cumulative hazard of HIV diagnosis following bacterial sexually transmitted infections (STI)

GC = gonorrhea. CT = chlamydial infection.

Figure 2. Number needed to treat (NNT) with HIV pre-exposure prophylaxis to directly prevent one new HIV infection by sexually transmitted infection type

Panel A: Primary analysis – Estimated from incidence of HIV diagnosis in Washington State Panel B: Sensitivity analysis – Estimated from incidence of HIV infection among MSM diagnosed at publicly funded HIV/STI testing programs MSM = men who have sex with men. GC = gonorrhea. CT = chlamydial infection. PrEP = HIV pre-exposure prophylaxis. This figure presents estimates of the number of HIV-negative MSM with each infection that would need to be treated with PrEP for one year in order to prevent one HIV infection among PrEP recipients (NNT) based on three estimates of PrEP effectiveness from iPrex: overall (44%; ■), with at least 90% adherence (73%; ●), and with detectable blood levels of PrEP drug (92%; ▲). Panel A shows NNTs estimated from the incidence of HIV diagnosis following STI diagnoses among all MSM in Washington State (primary analysis). Panel B presents estimates from the incidence of HIV infection among MSM diagnosed at publicly funded HIV/STI testing programs (sensitivity analysis). The date of HIV infection was estimated as the midpoint between the last negative and first positive HIV test from HIV surveillance, HIV partner services, or STI partner services data.

Figure 2. Number needed to treat (NNT) with HIV pre-exposure prophylaxis to directly prevent one new HIV infection by sexually transmitted infection type

Panel A: Primary analysis – Estimated from incidence of HIV diagnosis in Washington State Panel B: Sensitivity analysis – Estimated from incidence of HIV infection among MSM diagnosed at publicly funded HIV/STI testing programs MSM = men who have sex with men. GC = gonorrhea. CT = chlamydial infection. PrEP = HIV pre-exposure prophylaxis. This figure presents estimates of the number of HIV-negative MSM with each infection that would need to be treated with PrEP for one year in order to prevent one HIV infection among PrEP recipients (NNT) based on three estimates of PrEP effectiveness from iPrex: overall (44%; ■), with at least 90% adherence (73%; ●), and with detectable blood levels of PrEP drug (92%; ▲). Panel A shows NNTs estimated from the incidence of HIV diagnosis following STI diagnoses among all MSM in Washington State (primary analysis). Panel B presents estimates from the incidence of HIV infection among MSM diagnosed at publicly funded HIV/STI testing programs (sensitivity analysis). The date of HIV infection was estimated as the midpoint between the last negative and first positive HIV test from HIV surveillance, HIV partner services, or STI partner services data.

Figure 3. Proportion of 736 MSM newly diagnosed with HIV infection July 2011-June 2013 with a reported sexually transmitted infection diagnosis in the 2 years prior to HIV diagnosis

GC = gonorrhea. CT = chlamydial infection.