Dose-response effect of incarceration events on nonadherence to HIV antiretroviral therapy among injection drug users.

BACKGROUND: Although some studies have identified impressive clinical gains for incarcerated HIV-seropositive injection drug users (IDUs) undergoing antiretroviral therapy (ART), the effect of incarceration on adherence to ART remains undetermined. METHODS: We used data from a long-term community-recruited cohort of HIV-seropositive IDUs, including comprehensive ART dispensation records, in a setting where HIV care is free. We estimated the relationship between the cumulative burden of incarceration, measured longitudinally, and the odds of < 95% adherence to ART, with use of multivariate modeling. RESULTS: From 1996 through 2008, 490 IDUs were recruited and contributed 2220 person-years of follow-up; 271 participants (55.3%) experienced an incarceration episode, with the number of incarcerations totaling 1156. In a multivariate model, incarceration had a strong dose-dependent effect on the likelihood of nonadherence to ART: 1-2 incarceration events (adjusted odds ratio [AOR], 1.49; 95% confidence interval [95% CI], 1.03-2.05), 3-5 events (AOR, 2.48; 95% CI, 1.62-3.65), and > 5 events (AOR, 3.11; 95% CI, 1.86-4.95). CONCLUSIONS: Among HIV-seropositive IDUs receiving ART, an increasing burden of incarceration was associated with poorer adherence in a dose-dependent fashion. Our findings support improved adherence support for HIV-seropositive IDUs experiencing incarceration.