A randomized trial of lottery-based incentives and reminders to improve warfarin adherence: the Warfarin Incentives (WIN2) Trial

In Pharmacoepidemiology and Drug Safety, Stephen Kimmel and colleagues, including Jalpa Doshi, Benjamin French and Kevin Volpp, investigate the comparative effectiveness of reminders alone versus daily lottery incentives in improving medication adherence. This study was a four-arm multi-center randomized controlled trial including 270 patients on wafarin (anticoagulants), where patients were assigned to one of four groups: daily lottery based incentive, daily reminder, combination of the two, and a usual care control group. The lottery group was the only one with a significant improvement in incorrect adherence (12.1% VS 23.7% in the control group); however, the patients in the reminder group were the only ones with a significant improvement in auticoagulation control, measured as the lowest percentage of time out range of target international normalized ratio (odds of out-of-range INR 36% lower than control group). Thus, automated reminders led to the largest improvements in anticoagulation control (without affecting measured adherence), while lottery-based reminders improved measured adherence without changing anticoagulation control measures.