A randomized trial of direct-to-patient communication to enhance adherence to β-blocker therapy following myocardial infarction.

We conducted a cluster randomized controlled trial in 4 geographically dispersed health maintenance organizations testing the hypothesis that a simple direct-to-patient intervention could improve adherence. The study was carried out from June 2004 to March 2005. The primary analyses were based on 836 post-MI patients who were dispensed a beta-blocker prescription after discharge. The intervention consisted of 2 mailings 2 months apart describing the importance of beta-blocker use. The main outcomes were proportion of days covered with beta-blocker therapy and percentage of patients with at least 80% of days covered in the 9 months after the first mailing. Analyses were adjusted for age, sex, total medications dispensed, days between MI and intervention, and intervention site. Over the entire follow-up period, patients in the treatment arm had a mean absolute increase of 4.3% of days covered per month compared with patients in the control arm (a 5.7% relative change from baseline), representing 1.3 extra days (P = .04). Treatment patients were 17% more likely (relative risk, 1.17; 95% confidence interval, 1.02-1.29) to have 80% of days covered. For every 16 patients receiving the intervention, 1 additional patient would become adherent (80% or more days covered per month). A low-cost, easily replicable effort to increase adherence can have a demonstrable impact on beta-blocker adherence following MI.