Abstract and Introduction
The potential for human immunodeficiency virus (HIV) preexposure prophylaxis (PrEP) to reduce the racial disparities in HIV incidence in the United States might be limited by racial gaps in PrEP care. We used a network-based mathematical model of HIV transmission for younger black and white men who have sex with men (BMSM and WMSM) in the Atlanta, Georgia, area to evaluate how race-stratified transitions through the PrEP care continuum from initiation to adherence and retention could affect HIV incidence overall and disparities in incidence between races, using current empirical estimates of BMSM continuum parameters. Relative to a no-PrEP scenario, implementing PrEP according to observed BMSM parameters was projected to yield a 23% decline in HIV incidence (hazard ratio = 0.77) among BMSM at year 10. The racial disparity in incidence in this observed scenario was 4.95 per 100 person-years at risk (PYAR), a 19% decline from the 6.08 per 100 PYAR disparity in the no-PrEP scenario. If BMSM parameters were increased to WMSM values, incidence would decline by 47% (hazard ratio = 0.53), with an associated disparity of 3.30 per 100 PYAR (a 46% decline in the disparity). PrEP could simultaneously lower HIV incidence overall and reduce racial disparities despite current gaps in PrEP care. Interventions addressing these gaps will be needed to substantially decrease disparities.
Human immunodeficiency virus (HIV) prevalence among black men who have sex with men (BMSM) is 3–6 times as high as among white men who have sex with men (WMSM) across the United States, with incidence increasing among younger BMSM.[1,2] The causes of these disparities have been challenging to quantify. Although HIV medical care engagement has been worse for BMSM, behavioral studies consistently suggest lower HIV acquisition risks for BMSM than WMSM.[4,5] The US National HIV/AIDS Strategy has among its goals to reduce both new HIV diagnoses by 25% overall and racial disparities in diagnoses by 15% by 2020, with several strategies prioritized.
One high-priority intervention is scaling up HIV preexposure prophylaxis (PrEP), which has proven highly effective at lowering HIV risk. However, it is uncertain whether PrEP can be used to reduce HIV racial disparities. PrEP use by men who have sex with men (MSM) has increased nationally since US Food and Drug Administration approval. Pharmacy data indicate a 500% increase in PrEP prescriptions since 2014, but black persons received only 10% of those despite accounting for nearly half of recent HIV diagnoses.[2,8] Open-label PrEP studies have consistently highlighted challenges in reaching BMSM.[9–19] Reducing racial disparities in HIV incidence could be achieved with PrEP as part of a comprehensive HIV-prevention approach, but whether that is possible given the major gaps in PrEP care for BMSM remains a critical unanswered question.
A PrEP care-continuum framework conceptually defines these gaps. Kelley et al., for example, identified the steps towards complete HIV prevention with PrEP via awareness of PrEP, access to PrEP-related healthcare services, obtaining a PrEP prescription, and adherence after initiation. Their race-stratified estimates, based on data from an HIV cohort in Atlanta, Georgia, suggested that BMSM had equal or worse outcomes on all 4 steps. Nunn et al. included a fifth step: retention in PrEP care after effective adherence. Although a continuum framework does not directly solve the problem of how to close these gaps, it organizes research priorities and prevention efforts into distinct targets for intervention.
In this study, we used mathematical modeling to 1) quantify the PrEP-related reduction in HIV incidence for younger BMSM in the Southeastern United States over the next decade given current PrEP care-continuum estimates; and 2) predict how improvements along each continuum step (awareness, access, prescription, adherence, and retention) for BMSM, individually and jointly, could further reduce HIV incidence overall and disparities in HIV incidence between races. Although the levels of HIV disparities and scale-up of PrEP vary across health jurisdictions and risk groups in the United States, findings from this high-burden, low-resource target population may broadly inform intervention strategies through which PrEP could meet current HIV disparity reduction goals nationally.
Am J Epidemiol. 2019;188(4):743-752. © 2019 Oxford University Press