Electronic monitoring: adherence assessment or intervention?

Electronic-monitored adherence is often used as the primary outcome measure for evaluating adherence interventions. However, electronic monitoring may not only measure adherence, but may also improve or impede adherence, making it difficult to assess the extent to which the observed effect size is attributed to the intervention versus electronic monitoring. This study examined whether electronic monitoring and patient diaries alter as well as measure adherence.

A sample of 180 patients on highly active antiretroviral therapy (HAART) were randomized to one of three adherence surveillance methods (electronic monitoring caps, patient medication diaries, no surveillance control group) for 4 weeks, with adherence measured by a structured interview at baseline and study endpoint; 173 (96%) participants completed the study.

After controlling for baseline adherence, a univariate analyses of adherence at study endpoint revealed no significant differences across groups, F(2, 169) = 0.32, p =.73, with mean adherence rates of 91.4, 92.4, and 93.8 for the electronic monitoring, diaries, and control group, respectively. Similarly, the proportion of participants with good adherence (> or = 95%) did not differ significantly from baseline to week 4 among all three subgroups.

These results suggest that electronic monitoring caps and medication diaries do not alter adherence and can be used as outcome measures of interventions without the need to adjust the observed effect size.