Rates of antiretroviral resistance among HIV-infected patients with and without a history of injection drug use

BACKGROUND: There exist concerns regarding the potential for elevated rates of antiretroviral resistance among HIV-infected injection drug users (IDUs) prescribed highly active antiretroviral therapy (HAART), however, no population-based study has examined if IDUs have elevated rates of antiretroviral resistance in comparison to non-IDUs. OBJECTIVE: To evaluate the time to the development of antiretroviral resistance among antiretroviral-naive patients with and without a history of injection drug use. METHODS: In British Columbia there is a province-wide HIV/AIDS treatment program that provides antiretrovirals free of charge. We examined all antiretroviral-naive patients initiating HAART between 1 August 1996 and 30 September 2000 and who were followed to 31 March 2002. The main outcome measure was the time to class-specific antiretroviral resistance. Cumulative antiretroviral resistance rates among IDUs and non-IDUs were evaluated using Kaplan-Meier methods and relative hazards were estimated using Cox regression. RESULTS: Overall, 1191 antiretroviral-naive patients initiated HAART during the study period. Resistance mutations were observed in 298 (25%) subjects during the first 30 months of HAART. In comparison with non-IDUs, the risk of protease inhibitor resistance [relative hazard (RH), 0.9; 95% confidence interval (CI), 0.5-1.6] and non-nucleoside reverse transcriptase inhibitor resistance (RH, 1.5; 95% CI, 1.0-2.2) were similar among IDUs, and there were no differences in the rates of resistance to the sub-classes of nucleoside reverse transcriptase inhibitors. CONCLUSIONS: Resistance to all major classes of antiretrovirals were similar among IDUs and non-IDUs after 30 months of follow-up. These findings should help to allay fears that prescribing HAART to IDUs may result in elevated rates of resistance.