Retention in opioid substitution treatment: a major predictor of long-term virological success for HIV-infected injection drug users receiving antiretroviral treatment.

BACKGROUND The positive impact of opioid substitution treatment (OST) on opioid-dependent individuals with human immunodeficiency virus (HIV) infection is well documented, especially with regard to adherence to highly active antiretroviral therapy (HAART). We used the data from a 5-year longitudinal study of the MANIF 2000 cohort of individuals infected with HIV (as a result of injection drug use) and receiving HAART to investigate the predictors of long-term virological success. Design. Data were collected every 6 months from outpatient hospital services delivering HIV care in France. We selected all patients who were receiving HAART for at least 6 months (baseline visit) and who had indications for OST (ie, still dependent on opioids). We selected a total of 113 patients, accounting for a total of 562 visits for all the analyses. METHODS Long-term virological success was defined as an undetectable viral load after at least 6 months on HAART. Retention in OST was defined as the time interval between the last initiation or reinitiation of OST during HAART follow-up and any given visit on OST. A mixed logistic model was used to identify predictors of long-term virological success. RESULTS At baseline, 53 patients were receiving buprenorphine, 28 patients were receiving methadone, and 32 patients were not on OST. The median duration of OST was 25 months (range, 3-42 months). In the multivariate analysis, after adjustment for significant predictors of long-term virological success such as adherence to HAART and early virological response, retention in OST was associated with long-term virological success (odds ratio, 1.20 per 6-month increase; 95% confidence interval, 1.09-1.32). CONCLUSIONS Our study presents important evidence of the positive impact of retention in OST on HIV outcomes. Increasing access to OST based on a comprehensive model of care for HIV-infected patients who have indications for OST may foster adherence and ensure long-term response to HAART.