Understanding the HIV disparities between black and white men who have sex with men in the USA using the HIV care continuum: a modeling study.

BACKGROUND: Black/white disparities in HIV incidence and prevalence among men who have sex with men (MSM) in the United States remain largely unexplained. We examined the impact on HIV prevalence and incidence of interventions that decrease disparities in HIV care. Deciding which interventions have most impact on reducing disparities is critical.
METHODS: Using available US Centers for Disease Control and Prevention (CDC) estimates, we constructed HIV care continua for black and white MSM for 2009-2010. These estimates were used as parameters in a deterministic model to yield estimated race-specific transmissions, transmission rates, incidence rates, and rate-ratios (RR). We examined the impact of changes in the care continuum for black MSM on transmission and incidence rates.
FINDINGS: Marked disparities were found throughout the care continuum: ultimately, 16% of black and 34% of white MSM achieved viral suppression. Based on these care continua, 9,833 and 9,710 new HIV transmissions were estimated annually respectively from HIV-positive black and white MSM (transmission RR=1·36 and incidence RR=7·92). In a model where black and white MSM have identical care outcomes, transmission RR=1·00 and incidence RR=5·80. Scenarios of 95% diagnosis, 95% retention, and concurrent 95% diagnosis and 95% retention respectively yield transmission RR=1·00, 1·02, 0·56, and incidence RR=5·81, 5·93, 3·28.
INTERPRETATION: Disparities in HIV transmission rates may be reduced by improving the HIV care continuum outcomes, but existing racial disparities in HIV prevalence will likely continue to drive higher incidence among black MSM for decades to come.