Patient-Centered Interventions to Improve Adherence to Statins: A Narrative Synthesis of Systematically Identified Studies

Abstract

Poor adherence to statins increases cardiovascular disease risk. We systematically identified 32 controlled studies that assessed patient-centered interventions designed to improve statin adherence. The limited number of studies and variation in study characteristics precluded strict quality criteria or meta-analysis. Cognitive education or behavioural counselling delivered face-to-face multiple times consistently improved statin adherence compared with control groups (7/8 and 3/3 studies, respectively). None of four studies using medication reminders and/or adherence feedback alone reported significantly improved statin adherence. Single interventions that improved statin adherence but were not conducted face-to-face included cognitive education in the form of genetic test results (two studies) and cognitive education via a website (one study). Similar mean adherence measures were reported for 17 intervention arms and were thus compared in a sub-analysis: 8 showed significantly improved statin adherence, but effect sizes were modest (+7 to +22 % points). In three of these studies, statin adherence improved despite already being high in the control group (82-89 vs. 57-69 % in the other studies). These three studies were the only studies in this sub-analysis to include cognitive education delivered face-to-face multiple times (plus other interventions). In summary, the most consistently effective interventions for improving adherence to statins have modest effects and are resource-intensive. Research is needed to determine whether modern communications, particularly mobile health platforms (recently shown to improve medication adherence in other chronic diseases), can replicate or even enhance the successful elements of these interventions while using less time and fewer resources.

Fig. 1

Flow diagram of searches and the study selection process

Fig. 2

Combinations of components used in intervention groups (n = 34) to try to improve adherence to statins. Each column represents one intervention group. Intervention groups are ranked by the number of components involved. Components in each intervention group are illustrated by blue boxes (those in yellow boxes were applied to both the intervention group and the control group). Pink boxes highlight components that were not applied to all patients in the intervention group. Columns with interventions associated with a significant improvement in at least one measure of adherence are highlighted in green. Letters in boxes denote whether the component was used a single time (S) or multiple times (M). Symbols indicate who delivered the intervention: *physician; ^†pharmacist; and ^‡nurse. Roman numerals indicate the number of ‘other’ intervention components used. The full text of the descriptions of the interventions used in each study in relation to how they were categorized is provided in Supplementary Table 1 (online)

Fig. 3

Studies reporting the mean proportion of days covered, medication possession ratio or similar parameter by intervention type. 1 Cognitive education, 2 behavioural counselling, 3 treatment simplification, 4 medication reminders, 5 adherence feedback, A face-to-face, B telephone (person), C hard copy materials, D telephone (automated), E other delivery components (Roman numerals indicate number of other delivery components), S single time, M multiple times. *Statistically significant difference between control and intervention groups (p < 0.05)