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.