the Majority of Recent HIV Seroconversions Among MSM in the MACS. J Acquir Immune Defic Syndr.

the Majority of Recent HIV Seroconversions Among MSM in the MACS. J Acquir Immune Defic Syndr.

New HIV infections are being observed among men who have sex with men (MSM). Understanding the fusion of risky sexual behaviours, stimulant drug use, and erectile dysfunction drug use with HIV seroconversion may provide direction for focused intervention. During the follow-up period (1998-2008), Ostrow and colleagues identified 57 HIV seroconverters among 1667 initially HIV-seronegative men. Time to seroconversion was modelled using Cox proportional hazards regression analysis for 7 combinations of sex drugs (inhaled nitrites or “poppers”, stimulants, and erectile dysfunction drugs) used at the current or previous semi-annual visit, adjusting for other risk factors including sexual behaviour, alcohol and other drugs used, and depression. Model-based adjusted attributable risks were then calculated. The risk of seroconversion increased linearly with the number of unprotected receptive anal sex partners, with hazard ratios ranging from 1.73 [95% confidence interval (CI): 0.75 to 4.01] for 1 partner, to 4.23 (95% CI: 1.76 to 10.17) for 2-4 partners, and to 14.21 (95% CI: 6.27 to 32.20) for 5+ partners, independent of other risk factors. After adjustment, risks for seroconversion increased from 2.99 (95% CI: 1.02 to 8.76) for men who reported using stimulants only (1 drug) to 8.45 (95% CI: 2.67 to 26.71) for men who reported using all 3 sex drugs. The use of any of the 7 possible sex drug combinations accounted for 63% of the 9-year HIV seroincidence in the Multicenter AIDS Cohort Study. When contributions of increased unprotected receptive anal sex partners and combination drug use were analyzed together, the total attributable risk for HIV seroconversion was 74%, with 41% attributable to unprotected receptive anal sex partners alone and a residual of 33% due to other direct or indirect effects of sex drug use. Use of poppers, stimulants, and erectile dysfunction drugs increased risk for HIV seroconversion significantly in this cohort. These data reinforce the importance of implementing interventions that target drug reduction as part of comprehensive and efficacious HIV prevention strategies.

Editors’ note: Whether or not and how vasoactive sex drug use could increase the likelihood of HIV infection through unprotected sex, over and above the disinhibiting effects of drug use, is unclear. Nonetheless, the magnitude of the risk posed by the use of stimulant, poppers, and erectile dysfunction drugs is clear – among men who used all three drugs the relative hazard for HIV seroconversion was 8 times that of men who reported no use of these sex drugs. With noninjection substance use seemingly on the increase among men who have sex with men, particularly the use of erectile dysfunction drugs as men age, attention addressed to the linked epidemics of substance use and high-risk sex should inform tailored harm reduction and safer sex strategies.