Patterns of antiplatelet drug use after a first myocardial infarction during a 10-years period

AIMS: To assess antiplatelet use patterns after a first myocardial infarction (MI) and to evaluate the determinants of antiplatelet non-persistence.

METHODS: This study was conducted in 4,690 patients from the Utrecht Cardiovascular Pharmacogenetics cohort with first MI between 1986-2010, who were followed for a maximum of 10 years. Medication use and event diagnosis were obtained from the Dutch PHARMO Record Linkage System. Antiplatelet users were classified as persistent users (gap between prescriptions ≤ 90 days), non-persistent users (>90 days gap and no refills), and restarters (a new prescription after a > 90 days gap). The association between potential determinants and antiplatelet non-persistence was analysed with Cox regression.

RESULTS: The proportions of persistent users decreased from 84.0% at 1 year follow-up to 32.8% at 10 years for any antiplatelet drug, 77.3% to 27.5% for aspirin, and 39.0% to 6.4% for clopidogrel at 6 years. Most non-persistent users restarted antiplatelet drugs later, leading to 89.3% overall antiplatelet users at 10 years after MI. Diabetes (HR 0.44; 0.32-0.60), hypertension (HR 0.77; 0.60-0.99), hypercholesterolemia (HR 0.49; 0.39-0.62), and more recent MI diagnosis period lowered the risk of antiplatelet non-persistence, while vitamin K antagonist (VKA) co-medication (HR 18.97; 16.91-21.28) increased this risk.

CONCLUSIONS: A large proportion of patients with a first MI still used antiplatelet drugs after 10 years. The frequent discontinuations during this time-frame are expected to reduce the effectiveness of antiplatelet drugs as secondary prevention of cardiovascular diseases. Diabetes, hypertension, hypercholesterolemia, VKA co-medication, and MI diagnosis period were determinants of antiplatelet non-persistence. This article is protected by copyright. All rights reserved.