Medication Adherence Following Coronary Artery Bypass Graft Surgery: Assessment of Beliefs and Attitudes

Abstract

The medication management of patients following coronary artery bypass graft (CABG) surgery may include antiplatelet agents, beta-blockers, angiotensin-converting enzyme inhibitors, and statins. However, poor adherence is common, and patient attitudes and beliefs play a role in adherence. To evaluate the association between self-reported adherence and the beliefs patients have about cardiovascular medicines used after CABG. Adults were surveyed 6-24 months following CABG. The validated Beliefs about Medicines Questionnaire (BMQ) assessed attitudes concerning the Specific Necessity, Specific Concerns, General Harm, and General Overuse of medicines. The validated medication adherence scale assessed self-reported adherence. Analysis included univariate comparison (BMQ scales) and multivariate logistic regression (identification of adherence predictor variables). Of 387 patients surveyed, 132 (34%) completed the questionnaire. Nonparticipants were more likely to be female and have undergone 1- or 2-vessel CABG procedures compared with 3- or 4-vessel procedures. Subjects were primarily English-speaking, white, and male. Adherent behavior was reported in 73 of 132 patients (55%). The average period between CABG and the survey was 16 months. Nonadherent patients were in stronger agreement on the General Overuse (p = 0.01) and General Harm (p = 0.04) scales. The adjusted odds of adherent behavior were significantly lower, with an increasing General Overuse score (OR 0.83; 95% CI 0.72 to 0.95; p = 0.007); an annual income of $50,000 to $100,000 relative to less than $20,000 (OR 0.36; 95% CI 0.14 to 0.91; p = 0.031), and a living status of "alone" compared with "with adults and no children" (OR 0.20; 95% CI 0.06 to 0.65; p = 0.007). The odds ratio of self-reported adherence was higher with increasing age (OR 1.05; 95% CI 1.01 to 1.09; p = 0.023). In summary, patient beliefs and attitudes regarding medications, along with other social, economic, and demographic factors, help explain differences in self-reported adherence to standard drug therapy following CABG.