Improved adherence with contingency management.

Contingency management (CM) based interventions that reinforce adherence to prescribed medications have shown promise in a variety of disadvantaged populations. Fifty-six participants with histories of illicit substance use who were prescribed antiretroviral medication but evidenced suboptimal adherence during a baseline assessment were randomly assigned to 16 weeks of weekly CM-based counseling or supportive counseling, followed by 16 additional weeks of data collection and adherence feedback to providers. The CM intervention involved review of data generated by electronic pill-bottle caps that record bottle opening (MEMS) and brief substance abuse counseling. CM participants were reinforced for MEMS-measured adherence with drawings from a bowl for prizes and bonus drawings for consecutive weeks of perfect adherence. Potential total earnings averaged $800. Mean MEMS-measured adherence to the reinforced medication increased from 61% at baseline to 76% during the 16-week treatment phase and was significantly increased relative to the supportive counseling group (p = 0.01). Furthermore, mean log-transformed viral load was significantly lower in the CM group. However, by the end of the 16-week follow-up phase, differences between groups in adherence and viral load were no longer significantly different. Proportions of positive urine toxicology tests did not differ significantly between the two groups at any phase. A brief CM-based intervention was associated with significantly higher adherence and lower viral loads. Future studies should evaluate methods to extend effects for longer term benefits.