Background:  We have observed that the prevalence of primary drug resistance is higher in methamphetamine users. Similar biological and behavioral factors associated with methamphetamine use may lead to increased acquisition of HIV-1 drug-resistant mutations during ART. We evaluated whether methamphetamine users accumulated a greater number of HIV-1 drug-resistant mutations compared to non-methamphetamine users.

Methods:  We examined participants in a prospective clinic-based cohort of individuals with chronic HIV infection (SCOPE). Treatment-naïve participants on stable antiretroviral (ARV) regimens who had detectable viremia (>400 copies/mL) and ≥2 genotype results were included in the analysis. Methamphetamine use and treatment adherence data were self-reported by participants. Longitudinal multivariate analysis (GEE) was performed to assess the relationship between methamphetamine use and accumulation of HIV-1 drug-resistant mutations.

Results: At least 2 study visits were contributed to the dataset by 133 participants (range 2 to 12), for a total of 576 study visits (133 baseline, 443 follow-up). Median time between study visits was 124 days. Evidence of primary HIV-1 drug resistance was detected in 6% of participants at baseline. Current methamphetamine use, defined as any use in the 4 months preceding the study visit, was reported by 16% of participants. Increases in the number of drug-resistant mutations were observed at 20% of follow-up visits. At 93.3% of follow-up visits, participants reported <5% missed doses in the past 30 days. Methamphetamine users reported <5% missed doses at 92.1% of follow-up visits compared to 93.4% by non-methamphetamine users (p = 0.76). Methamphetamine use was not a predictor of an increased rate of accumulation of drug-resistant mutations (OR = 0.93, 95%CI 0.42 to 2.06; p = 0.76), even after controlling for baseline viral load, treatment adherence and time interval since HIV diagnosis (AOR = 1.12, 95%CI 0.33 to 3.77; p = 0.94).

Conclusions:  Our findings did not show an association between methamphetamine use and accumulation of a greater number of HIV-1 drug-resistant mutations. Treatment adherence was comparable between methamphetamine users and non-methamphetamine users. High adherence levels in our overall study population may account in part for the lack of association observed between methamphetamine use and increased acquisition of HIV-1 drug-resistant mutations.