Abstract
BACKGROUND: In the era of antiretroviral therapy (ART), depression and substance use predict hastened HIV disease progression, but the underlying biological or behavioral mechanisms that explain these effects are not fully understood. METHODS: Using outcome data from 603 participants enrolled in a randomized controlled trial of a behavioral intervention, binary logistic and linear regression were employed to examine whether inconsistent patterns of ART utilization partially mediated the effects of depression and substance use on higher HIV viral load over a 25-month follow-up. RESULTS: Elevated affective symptoms of depression independently predicted ART discontinuation [adjusted odds ratio = 1.39, 95% confidence interval (CI) = 1.08 to 1.78], and use of stimulants at least weekly independently predicted intermittent ART utilization (adjusted odds ratio = 2.62, 95% CI = 1.45 to 4.73). After controlling for the average self-reported percentage of ART doses taken and baseline T-helper (CD4) count, elevated depressive symptoms predicted a 50% higher mean viral load, and weekly stimulant use predicted a 137% higher mean viral load. These effects became nonsignificant after accounting for inconsistent patterns of ART utilization, providing evidence of partial mediation. CONCLUSIONS: Inconsistent patterns of ART utilization may partially explain the effects of depression and stimulant use on hastened HIV disease progression.