Estimating HIV protective effects of method adherence with combinations of preexposure prophylaxis and condom use among African American men who have sex with men.

BACKGROUND: Prevention of sexually acquired HIV infection now includes both consistent condom use and daily use of oral antiretroviral preexposure prophylaxis (PrEP). Persons at substantial HIV risk can now use one or both prevention methods, but a combined HIV protective effect has not been assessed.
METHODS: We use deterministic models to examine the impact of method adherence and rates of PrEP and male condom use on number of anticipated HIV infections. Analyses were based on hypothetical cohorts of 10,000 African American men who have sex with men (AAMSM), a population with the highest HIV incidence in the United States. Parameters used in the model (condom effectiveness, PrEP effectiveness, HIV incidence) were based on published findings.
RESULTS: Among AAMSM who never use PrEP, an estimated 323 annual HIV infections would occur among those who always use condoms, 1007 among sometimes condom users, and 1094 among never condoms users. Among AAMSM who never (or inconsistently) use condoms, 295 (272) infections would occur among those who report at least 90% PrEP adherence and 744 (684) infection occur with less than 50% adherence. Among AAMSM who are consistently (or sometimes) taking PrEP, the highest protection is seen with consistent condom use, 87 (220) HIV infections and 92.0% (79.9%) prevention effectiveness. DISCUSSION: Among AAMSM with inconsistent or never condom use, the addition of PrEP at either modest or high adherence can increase HIV protection. For consistent condom users, any PrEP use can increase HIV protection. These analyses provide an approach for rethinking HIV risk management by calculating combined HIV protective effects of using one or more effective prevention methods.