A hybrid 4-item Krousel-Wood Medication Adherence Scale predicts cardiovascular events in older hypertensive adults

Background: There is a need for a brief, open access, self-report medication adherence scale that overcomes challenges of existing adherence tools, is associated with incident cardiovascular disease (CVD), and identifies low 'implementation' adherers to antihypertensive medications to facilitate blood pressure management.Methods and results:Antihypertensive medication adherence was assessed in a cohort of 1532 older hypertensive adults without prior CVD using the self-report 4-item Krousel-Wood Medication Adherence Scale (K-Wood-MAS-4), a hybrid tool developed to predict pharmacy refill and which captures four domains of adherence behavior: self-efficacy, physical function, intentional medication-taking, and forgetfulness. The 4-item scale categorized participants as low and high adherers using scores at least 1 and less than 1, respectively. Participants were followed after K-Wood-MAS-4 assessment to identify incident CVD events (stroke, myocardial infarction, congestive heart failure, or CVD death). The prevalence of low adherence was 38.7%. During a median follow-up of 2.8 years (maximum 3.8 years), 136 (8.9%) participants had an incident CVD event; 12.8 and 6.4% in low and high adherers, respectively. The adjusted hazard ratio (aHR) for incident CVD associated with low versus high adherence was 2.29 [95% confidence interval (CI): 1.61, 3.26]. Results were similar when stratified by age [<75 years - aHR 3.53 (95% CI: 1.65, 7.56); ≥75 years - aHR 1.98 (95% CI: 1.32, 2.97)], sex [women - aHR 1.90 (95% CI: 1.16, 3.12); men - aHR 2.80 (95% CI: 1.68, 4.65)], and race [black - aHR 2.22 (95% CI: 0.93, 5.31); white - aHR 2.26 (95% CI: 1.54, 3.34)].Conclusion:Low medication adherence using the 'hybrid' K-Wood-MAS-4 predicts incident CVD in a cohort of older adults with established hypertension.