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Virologic Failure Rate No Higher in Blacks Than Whites in US Military
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IDWeek 2018, October 3-7, 2018, San Francisco
Mark Mascolini
Contradicting some earlier research, African Americans did not run a greater risk of virologic failure than whites in a 5-year analysis of 1470 US Department of Defense beneficiaries, who have unrestricted access to care [1]. Older age, better adherence, and taking an integrase inhibitor independently predicted a lower risk of virologic failure.
Prior research from several groups found that African Americans reach an undetectable viral load less often than other racial/ethnic groups, have higher rebound rates if they do attain an undetectable load, and have higher HIV-related death rates. Investigators from the Henry M. Jackson Foundation and other military groups who conducted this study noted that several factors may contribute to such findings in blacks, including poverty, lack of access to care and antiretroviral therapy (ART), longer HIV duration before starting ART, and differences in antiretroviral adherence and retention in care.
To determine whether race-related virologic failure disparities persist in the latest antiretroviral era, these researchers focused on US Department of Defense beneficiaries, who include a high proportion of blacks. But this black HIV group differs from many others in the United States because they have routine HIV testing, typically start ART promptly after diagnosis, and have limited barriers to ART and overall care.
The analysis focused on people who contributed follow-up after January 2001 to the US Military Natural History Study (NHS), a longitudinal cohort. The researchers used medical records to gather demographics, ART history, and viral loads over time. They based adherence analyses on pharmacy records. Virologic failure meant 2 consecutive viral loads at or above 200 copies or 1 viral load above 1000 copies 6 or more months after starting ART and while taking ART. The investigators used a Cox model with time-updated covariates to identify independent predictors of virologic failure.
The study included 1470 military beneficiaries, 96% of them men, 612 (42%) African American, 557 (38%) white, and 301 (20%) Hispanic. When ART began median age stood at 30.6 years, viral load at 4.6 log10 copies (about 40,000 copies), and CD4 count at 370. During a median 4.7 years of follow-up, 132 participants (9%) met virologic failure criteria.
Virologic failure proved significantly more frequent among blacks (11.4%) than among whites (7%) or Hispanics (7.6%) (P = 0.0198). But the Cox model accounting for other potential virologic failure factors found that race did not independently predict failure. Compared with blacks, whites had a nonsignificantly lower risk of failure (adjusted hazard ratio [aHR] 0.726, 95% confidence interval [CI] 0.466 to 1.131, P = 0.16), while Hispanics had a nonsignificantly higher risk of failure (aHR 1.107, 95% CI 0.673 to 1.822, P = 0.69).
This multivariate analysis did find other independent predictors of failure. Every additional 10 years of age lowered failure risk about 25% (P = 0.02). Every 10-fold higher viral load when ART began raised failure risk 30% (P = 0.01), while every 100-cell higher CD4 count when treatment began tended to trim failure risk almost 10% (P = 0.06). Taking single or double antiretrovirals before starting combination ART doubled the risk of failure (P = 0.0085). Compared with taking a boosted protease inhibitor, taking an integrase inhibitor more than halved failure risk (P = 0.04). And at least 90% ART adherence, compared with less, more than halved failure risk (P = 0.0003).
The researchers stressed that the slightly higher overall failure rate among blacks than whites or Hispanics did not translate into an independently higher failure risk in the multivariate analysis. They observed that blacks tended to have higher prevalence of other failure risk factors: younger age at HIV diagnosis and ART initiation, delays in starting ART, and lower adherence. Although blacks in the military have the same antiretroviral access as other groups, 13% of blacks versus 6% of whites had adherence levels below 90%. The investigators suggested that future studies "examine whether factors such as mistrust of the medical establishment may also be at play in the Natural History Study."
Reference
1. Ganesan A, Won S, Christie Joya C, et al. In a well characterized cohort with universal access to care and medications racial disparities in HIV virologic outcomes are no longer observed. IDWeek 2018, October 3-7, 2018, San Francisco. Abstract 571.
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