Explaining racial disparities in HIV incidence in black and white men who have sex with men in Atlanta, GA: a prospective observational cohort study

Abstract

Purpose: To describe factors associated with racial disparities in HIV (human immunodeficiency virus) incidence among men who have sex with men (MSM) in the United States.

Methods: In a longitudinal cohort of black and white HIV-negative MSM in Atlanta, HIV incidence rates were compared by race. Incidence hazard ratios (HRs) between black and white MSM were estimated with an age-scaled Cox proportional hazards model. A change-in-estimate approach was used to understand mediating time-independent and -dependent factors that accounted for the elevated HR.

Results: Thirty-two incident HIV infections occurred among 260 black and 302 white MSM during 843 person-years (PY) of follow-up. HIV incidence was higher among black MSM (6.5/100 PY; 95% confidence interval [CI]: 4.2-9.7) than white MSM (1.7/100 PY; CI: 0.7-3.3) and highest among young (18-24 years) black MSM (10.9/100 PY; CI: 6.2-17.6). The unadjusted hazard of HIV infection for black MSM was 2.9 (CI: 1.3-6.4) times that of white MSM; adjustment for health insurance status and partner race explained effectively all of the racial disparity.

Conclusions: Relative to white MSM in Atlanta, black MSM, particularly young black MSM, experienced higher HIV incidence that was not attributable to individual risk behaviors. In a setting where partner pool risk is a driver of disparities, it is also important to maximize care and treatment for HIV-positive MSM.

Keywords: Cohort studies; HIV incidence; Men who have sex with men; Racial disparities.

Figure 1

STROBE diagram for an HIV/STI incidence cohort of black and white non-Hispanic MSM followed in Atlanta, 2010–2014 ^*6 participants with acute infections at baseline continued to be followed prospectively

Figure 2

Kaplan Meier plots illustrating incident HIV infection in 562 black and white non-Hispanic MSM followed in an HIV/STI incidence cohort, Atlanta, 2010–2014

Figure 3

Adjusted black-white hazard ratios for HIV infection from multivariable models, in a cohort study of 562 black and white non-Hispanic MSM, in an HIV/STI incidence cohort, Atlanta, 2010–2014 a. Adjusted HR for race not estimable due to lack of incident infections among those reporting injecting drug use b. Yellow region indicates covariate-adjusted HR for race that are between 0% and 10% less than the HR for race without covariate adjustment, whereas green region indicates covariate-adjusted HR that are more than 10% less, indicating meaningful mediation of the race disparity in HIV incidence.