Abstract
This study was conducted to examine the relationship between adherence, viral load (VL) and resistance among outpatients receiving highly active antiretroviral therapy (HAART) in Bangalore, India. In total, 552 outpatients were recruited and VL testing was conducted for all study participants. HIV-1 genotypic resistance testing was performed for 92 participants with a VL ≥ 1000 copies/ml. Interpretation of resistance mutations was performed according to the Stanford database. Past-month adherence and treatment interruptions for >48 h were assessed via self-report. At baseline, 34 participants (6%) reported <95% past-month adherence and 110 (20%) reported a history of >48 h treatment interruptions. Combining the two adherence measures, 22% of participants were classified as 'suboptimally adherent'. In total, 24% of study participants (n = 132) had a detectable VL. Among the 92 samples sent for resistance testing, 68% had at least one nucleoside reverse transcriptase inhibitor (NRTI) mutation, with M184V being the most common (62%) and with 48% having thymidine analogue mutations. Moreover, 72% had at least one non-nucleoside reverse transcriptase inhibitor (NNRTI) mutation and 23% had three or more NNRTI mutations. Both adherence measures were significantly associated with VL (P < 0.001). Suboptimal adherence was significantly associated with resistance mutations (P < 0.02). The findings illustrate for the first time the strong association between suboptimal adherence, treatment failure and drug resistance to first-line HAART in India. The predictive value of standard adherence measures was improved by including treatment interruption data. The observed mutations can jeopardise future treatment options, especially in light of limited access to second-line treatments. To develop effective adherence interventions, research is needed to examine culturally-specific reasons for treatment interruptions.