Adherence to secondary prevention medicines by coronary heart disease patients. First Reported Adherence

Abstract

Background Non-adherence to evidence based secondary prevention medicines (SPM) by coronary heart disease (CHD) patients limits their expected benefits and may result in a lack of improvement or significant deterioration in health. This study explored self-reported non-adherence to SPM, barriers to adherence, and the perception that patients in West Yorkshire have about their medicines in order to inform practice and improve adherence.

Methods In this cross-sectional study a specially designed postal survey (The Heart Medicines Survey) assessed medicines-taking behaviour using the Morisky Medicines Adherence 8 items Scale (MMAS-8), a modified version of the Single Question Scale (SQ), the Adherence Estimator (AE), Beliefs about Medicines Questionnaire(BMQ) and additional questions to explore practical barriers to adherence. Patients were also asked to make any additional comments about their medicines-taking experience. A purposive sample of 696 patients with long established CHD and who were on SPM for at least 3 months was surveyed. Ethical approval was granted by the local ethics committee.

Results 503 (72%) patients participated in the survey. 52%, 34% and 11% of patients were prescribed at least four, three and two SPMs respectively. The level of non-adherence to collective SPM was 44%. The AE predicted that 39% of those had an element of intentional non-adherence. The contribution of aspirin, statins, clopidogrel, beta blockers, angiotensin converting enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARBs) to overall non-adherence as identified by the SQ scale was 62%, 67%, 7%, 30%, 22% and 5%, respectively. A logistic regression model for overall non-adherence revealed that older age and female gender were associated with less non-adherence (OR = 0.96, 95% CI: 0.94, 0.98; OR = 0.56, 95% CI: 0.34, 0.93; respectively). Specific concern about SPM, having issues with repeat prescriptions and aspirin were associated with more non-adherence (OR = 1.12, 95% CI: 1.07, 1.18; OR = 2.48, 95% CI: 1.26, 4.90, OR = 2.22, 95% CI: 1.18, 4.17). Other variables were associated with intentional and non-intentional non-adherence. 221 (44%) patients elaborated on their medicines-taking behaviour by providing additional comments about the need for patient tailored information and better structured medicines reviews.

Conclusions The Medicines Heart Survey was successful in revealing the prevalence of self-reported non-adherence and barriers to adherence in our population. Healthcare professionals should examine specific modifiable barriers to adherence in their population before developing interventions to improve adherence. Conducting frequent structured medicines-reviews, which explore and address patients' concerns about their medicines and healthcare services, and enable them to make suggestions, will better inform practice and may improve adherence.