BACKGROUND: Many antiretroviral treatment (ART) adherence measurement methods have been employed by different studies, but no single method has been found to be appropriate for all settings. This study aimed to determine baseline levels of adherence using 2 measures of adherence.
METHODS: Levels of adherence in 967 patients continuing to receive ART in 4 health facilities were assessed over a 28-week period using a clinic-based pill count method and a patient self-report questionnaire. Factors associated with adherence were also determined.
RESULTS: Mean adherence (95% confidence interval) was 97.3% (96.8% to 97.9%) and 98.4% (97.9% to 98.8%) for the clinic-based pill count and patient self-report methods, respectively. Proportion of clients achieving optimal adherence (≥ 95%) was 89.9% by pill count and 94.2% by self-report. The 2 adherence measures were closely correlated with each other (r = 0.87, P = 0.000). Adherence increased with age (P = 0.014) with patients aged 40 years and below being less likely to achieve optimal adherence [odds ratio = 0.55; 95% confidence interval (0.34 to 0.89)].
CONCLUSIONS: There is a very high level of optimal adherence among patients still on treatment. The combined use of these 2 replicable and reliable methods of measuring adherence is vital to ART programs in resource-constrained settings.