Targeting pre-exposure prophylaxis among men who have sex with men in the United States and Peru: partnership types, contact rates, and sexual role.
BACKGROUND
We aim to identify optimal strategies for deploying pre-exposure prophylaxis among men who have sex with men (MSM) in the United States and Peru to maximize population-level effectiveness in an efficient manner. We use epidemic models to simulate the impact of targeting strategies. Most studies have focused on targeting either the general population or high-risk MSM. Alternative strategies, including serodiscordant couples, may better balance effectiveness and efficiency.


METHODS
We use dynamic stochastic sexual network models based on exponential-family random graph modeling, parameterized from behavioral surveys of MSM in the United States and Peru. These models represent main partnerships and casual contacts separately, permitting modeling of interventions targeting men whose risk derives from combinations of relational types. We also model varying rates of uptake and adherence to pre-exposure prophylaxis (PrEP). We assess sensitivity of results to risk compensation through increases in condomless casual contacts and condomless sex in main partnerships.


RESULTS
Targeting all men who are not exclusively insertive has the largest impact on HIV incidence, but targeting only those with high levels of casual activity yields comparable results using fewer person-years on PrEP. The effect is robust to risk compensation in the United States, but less so in Peru. Targeting serodiscordant main partnerships does not significantly impact incidence, but requires fewer person-years on PrEP per infection averted than other strategies.


CONCLUSIONS
PrEP could be effective in reducing new infections at the population level in both settings. Serodiscordant partnerships are an attractive component of a targeting program, but targeting should include other high-risk men.
*Joseph J. Zilber School of Public Health, University of Wisconsin-Milwaukee, Milwaukee, WI; †Department of Anthropology, University of Washington, Seattle, WA; ‡San Francisco Department of Public Health, San Francisco, CA; §Department of Epidemiology & Biostatistics, University of California San Francisco School of Medicine, San Francisco, CA; and ‖Asociacion Civil Impacta Salud y Educacion, Lima, Peru.
Nicole B
NB
Carnegie
Steven M
SM
Goodreau
Albert
A
Liu
Eric
E
Vittinghoff
Jorge
J
Sanchez
Javier R
JR
Lama
Susan
S
Buchbinder
D056808:Biostatistics / Q000379:methods; D018562:Disease Transmission, Infectious / Q000517:prevention & control*; D004812:Epidemiologic Methods; D015658:HIV Infections / Q000517:prevention & control* / Q000635:transmission*; D018451:Homosexuality, Male; D006801:Humans; D008297:Male; D010568:Peru; D065129:Pre-Exposure Prophylaxis / Q000379:methods*; D014481:United States