The interaction of active substance use, depression, and antiretroviral adherence in methadone maintenance.

Abstract

Adherence to highly active antiretroviral therapy (HAART) remains crucial in successfully treating HIV. While active substance use and depression are both associated with each other and with HAART nonadherence, little is known about their interaction. An understanding of the interaction of substance use and depressive symptoms on HAART adherence can inform adherence-enhancing interventions as well as interventions that target substance use and depression. We tested an interaction between substance use and depression on HAART adherence among methadone maintenance patients. We assessed substance use, depressive symptoms, and HAART adherence among 100 HIV-infected individuals receiving methadone maintenance in The Bronx, New York. Regressions were performed on adherence using an interaction term comprised of substance use and depressive symptoms. MODPROBE was used to assess significant interactions. Any use of illicit substances was associated with HAART nonadherence (p = 0.043). Cannabis was the single substance of abuse most strongly associated with nonadherence (p = 0.003). Depressive symptoms approached significance in bivariate analysis (p = 0.066). In regression analysis, a significant interaction was found between illicit substance use and depressive symptoms [OR (95% CI) 1.23 (1.06-1.44), p = 0.007], where illicit substance use was associated with nonadherence in individuals with lower depressive symptoms, but not among those with depressive symptoms at higher levels. No individual substances interacted with depressive symptoms on adherence. Though substance use and depressive symptoms interacted on HAART adherence, they did not have a synergistic effect. Continued substance use (51% of the sample) suggests an unmet need for treatment, even in methadone maintenance. Further examinations of the interplay of substance use and depression on HAART adherence are warranted.