Background: The use of antiretroviral (ARV) medications is expanding rapidly in Thailand. The determinants of optimal adherence for HIV-positive patients in Thailand are unknown.
Methods: A sample of 149 Thai patients receiving ARV therapy at Bhumrasnaradura Infectious Disease Institute located near Bangkok completed a structured questionnaire and reported medication adherence on a 30 day visual analog scale. HIV RNA test results were abstracted from the medical record.
Results: Adherence ranged from 25% to 100%. The median was 100% and the mean was 96%. The majority of subjects (114, 77%) had an HIV RNA </=50 copies/mL. An undetectable viral load was associated with adherence >/=95% (odds ratio [OR] = 3.0; 95% confidence interval [CI] 1.3 to 7.1; P = 0.02) and with a lower mean number of months on ARV therapy (22 versus 32 months; P = 0.03). Gender, educational level, method of payment, use of GPO-VIR, and whether or not the patient was on his or her initial ARV regimen were not associated with an undetectable viral load. In the multivariate analysis, only length of time in months was associated with an undetectable viral load. For each additional month, the odds of being undetectable were 0.975. (OR = 0.975; 95% CI 0.954 to .996; P = 0.02).
Conclusions: Adherence was high in this cohort and was associated with HIV-RNA levels. However, these data confirm that adherence is only 1 factor that determines the effectiveness of ARV treatment. Duration of treatment was associated with virologic failure, controlling for adherence.