Directly observed antiretroviral therapy in substance abusers receiving methadone maintenance therapy does not cause increased drug resistance

Direct observation of antiretroviral therapy (DOT) can increase adherence rates in HIV-infected substance users, but whether this affects the development of antiretroviral drug resistance has not been fully explored. We conducted a 24-week randomized controlled trial of methadone clinic-based antiretroviral DOT compared with treatment as usual (TAU) among antiretroviral-experienced substance users. To examine the development of new resistance mutations, we identified all participants with an amplifiable resistance test at both baseline and either week 8 or week 24. We compared the development of new drug resistance mutations between participants in the two arms of the trial. Among the 77 participants enrolled in the parent trial, antiretroviral DOT was efficacious for improving adherence and decreasing HIV viral load. Twenty-one participants had a detectable HIV viral load at both baseline and a second time point. Of these, nine developed new drug resistance mutations not seen at baseline (three in the DOT arm and six in the TAU arm; p = 0.27). Overall, five subjects in the TAU arm developed major mutations correlating with their current antiretroviral regimen, while no subjects in the DOT arm developed such mutations. Direct observation of antiretroviral therapy was associated with improved adherence and viral suppression among methadone maintained HIV-infected substance users, but was not associated with an increase in the development of antiretroviral drug resistance. DOT should be considered for substance users attending methadone maintenance clinics who are at high risk of nonadherence.