Assessment of adherence to statin therapy in patients with coronary artery disease: comparison of three self-reporting measures

OBJECTIVES: To investigate adherence to statin therapy using three self-reporting adherence measures in patients with coronary artery disease and to compare the three measures. METHODS: A cross-sectional study was carried out at a multidisciplinary outpatient clinic of cardiology at a teaching hospital in south-eastern Brazil in patients with coronary artery disease who were using statins. The sample consisted of 148 patients who were selected from April 2018 to February 2019. Adherence to statin therapy was determined by the Measure of Adherence to Treatment, Visual Analogue Scale of adherence and 7-day recall. A descriptive analysis and determination of the level of agreement between the adherence scales by the Cohen kappa coefficient were performed. RESULTS: The study included 148 patients (104 (70.3%) men, median age 62 years) diagnosed with coronary artery disease who were using statins. The adherence to statin therapy was 98.6% using the Measure of Adherence to Treatment, 95.9% with the Visual Analogue Scale and 95.3% with 7-day recall. Agreement between the Measure of Adherence to Treatment and the Visual Analogue Scale (0.277) and the Measure of Adherence to Treatment and 7-day recall (0.241) was low. There was a high level of agreement between the Visual Analogue Scale and 7-day recall (0.759). CONCLUSIONS: The adherence Visual Analogue Scale and 7-day recall were shown to be easy to apply, low-cost adherence measures to identify adherence to statins in patients with coronary artery disease. The Measure of Adherence to Treatment may also be used to provide information regarding the specific reasons for non-adherent behaviour.