ABSTRACT

Apixaban is non-inferior to warfarin in the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation. The clinical use of apixaban in older patients is carefully regulated by the Health Insurance Review and Assessment Service in South Korea, due to a high bleeding risk. This study aimed to evaluate the patterns of apixaban use and medication adherence. A retrospective study was conducted using the electronic medical record (EMR). The study included patients who were 65 years and older with non-valvular atrial fibrillation who were prescribed apixaban from July 1, 2016, to June 30, 2017, in an ambulatory care setting in the Seoul National University Bundang Hospital. We assessed apixaban usage, concomitant medications, and adverse events based on information from the Ministry of Food and Drug Safety. The medication adherence was calculated by cumulative medication adherence (CMA), with appropriate medication adherence defined as a CMA equal to or higher than 80 percent. Among the 553 eligible patients, 243 patients were excluded because they were prescribed apixaban during hospitalization, baseline data were unavailable, or they were lost to follow-up. A total of 310 patients were analyzed for the study. The mean age was 76.6 years. Of these, 52.6% of patients used low dose apixaban. A total of 309 (99.7%) patients were covered by the National Health Insurance. The rate of concurrent use of antiplatelet therapy was 13.2 percent. Adverse events were reported in 17 (5.5%) patients, and were mostly non-major bleeding events. The appropriate medication adherence rate was 93.2 percent. This study showed that the rates of National Health Insurance coverage and medication adherence were more than 90 percent. In real clinical practice, low doses of apixaban were used more than 50% because of the bleeding risk in older aged patients. Because long-term use of apixaban is prescribed for elderly patients with non-valvular atrial fibrillation, pharmacists must take active roles in counseling and close monitoring of adverse events to improve medication adherence.

KEYWORD

Apixaban, Drug utilization review, Medication adherence

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