Improving Medication Adherence through Graphically Enhanced Interventions in Coronary Heart Disease (IMAGE-CHD): A Randomized Controlled Trial

Abstract

Up to 50 % of patients do not take medications as prescribed. Interventions to improve adherence are needed, with an understanding of which patients benefit most. To test the effect of two low-literacy interventions on medication adherence. Randomized controlled trial, 2 × 2 factorial design. Adults with coronary heart disease in an inner-city primary care clinic. For 1 year, patients received usual care, refill reminder postcards, illustrated daily medication schedules, or both interventions. The primary outcome was cardiovascular medication refill adherence, assessed by the cumulative medication gap (CMG). Patients with CMG<0.20 were considered adherent. We assessed the effect of the interventions overall and, post-hoc, in subgroups of interest. Most of the 435 participants were elderly (mean age=63.7 years), African-American (91 %), and read below the 9th-grade level (78 %). Among the 420 subjects (97 %) for whom CMG could be calculated, 138 (32.9 %) had CMG<0.20 during follow-up and were considered adherent. Overall, adherence did not differ significantly across treatments: 31.2 % in usual care, 28.3 % with mailed refill reminders, 34.2 % with illustrated medication schedules, and 36.9 % with both interventions. In post-hoc analyses, illustrated medication schedules led to significantly greater odds of adherence among patients who at baseline had more than eight medications (OR=2.2; 95 % CI, 1.21 to 4.04) or low self-efficacy for managing medications (OR=2.15; 95 % CI, 1.11 to 4.16); a trend was present among patients who reported non-adherence at baseline (OR=1.89; 95 % CI, 0.99 to 3.60). The interventions did not improve adherence overall. Illustrated medication schedules may improve adherence among patients with low self-efficacy, polypharmacy, or baseline non-adherence, though this requires confirmation.