Antiretroviral therapy adherence and viral suppression in HIV-infected drug users: Comparison of self-report and electronic monitoring

To compare electronically monitored (MEMS) with self-reported adherence in drug users, including the impact of adherence on HIV load, we conducted a 6 -month observational study of 67 antiretroviral-experienced current and for mer drug users. Adherence (percentage of doses taken as prescribed) was cal culated for both the day and the week preceding each of 6 research visits. Mean self-reported 1-day adherence was 79% (median, 86%), and mean self-rep orted 1-week adherence was 78% (median, 85%). Mean MEMS 1-day adherence was 57% (median, 52%), and mean MEMS 1-week adherence was 53% (median, 49%). O ne-day and 1-week estimates were highly correlated ( for both measures). Bo th self-reported and MEMS adherence were correlated (r>.8 with concurrent H IV load (r = .143-.60), but the likelihood of achieving virologic suppressi on was greater if MEMS adherence was high than if self-reported adherence w as high. We conclude that self-reported adherence is higher than MEMS adher ence, but a strong relationship exists between both measures and virus load . However, electronic monitoring is more sensitive than self-report for the detection of nonadherence and should be used in adherence intervention stu dies.