Adherence to Medications by Patients After Acute Coronary Syndromes

Background: Nonadherence to medication may lead to poor medical outcomes.

Objective: To describe medication-taking behavior of patients with a history of acute coronary syndromes (ACS) for 4 classes of drugs and determine the relationship between self-reported adherence and patient characteristics.

Methods: Consenting patients with the diagnosis of ACS were interviewed by telephone approximately 10 months after discharge. The survey elicited data characterizing the patient, current medication regimens, beliefs about drug therapy, reasons for discontinuing medications, and adherence. The survey included the Beliefs About Medicine Questionnaire providing 4 scales: Specific Necessity, Specific Concerns, General Harm, and General Overuse, and the Medication Adherence Scale (MAS). Multivariate regression was used to determine the independent variables with the strongest association to the MAS. A p value < or = 0.05 was considered significant for all analyses.

Results: Two hundred eight patients were interviewed. Mean +/- SD age was 64.9 +/- 13.0 years, with 60.6% male, 95.7% white, 57.3% with a college education, 87.9% living with > or =1 other person, and 42% indicating excellent or very good health. The percentage of patients continuing on medication at the time of the survey category ranged from 87.4% (aspirin) to 66.0% (angiotensin-converting enzyme inhibitors). Reasons for stopping medication included physician discontinuation or adverse effects. Of patients still on drug therapy, the mean MAS was 1.3 +/- 0.4, with 53.8% indicating nonadherence (score >1). The final regression model showed R(2) = 0.132 and included heart-related health status and Specific Necessity as significant predictor variables.

Conclusions: After ACS, not all patients continue their drugs or take them exactly as prescribed. Determining beliefs about illness and medication may be helpful in developing interventions aimed at improving adherence.