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

Background Disparities in HIV incidence and prevalence between black and white men who have sex with men (MSM) in the USA remain largely unexplained. We assessed the effect of interventions for black MSM that might reduce disparities in HIV care continuum and incidence in MSM. Methods Using data from the US Centers for Disease Control and Prevention (CDC), we constructed the HIV care continuum for black and white MSM for 2009-10. These data were used in a deterministic model to estimate racespecific transmissions, transmission rates, incidence rate, and rate ratios. Findings Disparities were noted throughout the care continuum, with 28 251 (16%) of 180 477 black MSM and 83 223 (34%) of 243 174 white MSM achieving viral suppression. An estimated 9833 and 9710 new HIV transmissions per year were attributable to HIV-positive black and white MSM, respectively (transmission rate ratio 1 . 36 and incidence rate ratio 7.92). In a model in which black and white MSM had identical care outcomes, the transmission rate ratio was 1.00 and incidence rate ratio was 5.80. In scenarios of 95% diagnosis, 95% retention, and concurrent 95% diagnosis and 95% retention, the transmission rate ratios were 1.00, 1.02, and 0.56, respectively, and incidence rate ratios were 5.81, 5.93, and 3.28, respectively. Interpretation Disparities in the rates of HIV transmission could be reduced by improving the outcomes of the HIV care continuum, but racial disparities in HIV prevalence are likely to continue sustaining the higher incidence in black MSM for decades to come.