Placebo Practice Trials: The Best Predictor of Adherence Readiness for HAART Among Drug Users?

Abstract

Purpose: This study assessed the utility of a placebo practice trial in determining adherence readiness among drug users. Method: Participants with histories of drug dependency completed a 2-week practice trial that mimicked HAART (Phase 1), followed by a 2-week observation of adherence to HAART (Phase 2) for those who began antiretroviral therapy during the study period. The primary measure of adherence was electronic monitoring. Results: There were 201 participants enrolled; 39% met criteria for current drug dependency. Mean adherence to the practice trial was 67%. Of the 184 Phase 1 completers, 83 (45%) initiated HAART prior to the end of the study. Mean adherence to HAART was 74%, including 33 patients (39%) with 90+% adherence. Adherence to the practice trial was correlated with antiretroviral adherence (r = .49, p < .001), and 90+% adherence to the practice trial was an accurate marker of the "adherence readiness" (ability to adhere 90+% on HAART) of 72% of the participants. In multivariate analyses, practice trial adherence was the best independent predictor of antiretroviral adherence, accounting for 19% of the explained variance; other predictors included adherence to recent clinic appointments, cognitive functioning, unstable housing, and adherence self-efficacy. Conclusion: These findings suggest that a brief placebo practice trial has the potential to provide clinicians and patients with an accurate screening tool for evaluating adherence readiness.