Prevalence and associated factors of premature discontinuation of antiplatelet therapy after ischemic stroke: a nationwide population-based study

BACKGROUND: We tried to evaluate the prevalence of premature discontinuation of antiplatelets and its affecting factors after ischemic stroke using large-sized representative national claims data. METHODS: Patients aged 20 years or older with newly confirmed ischemic stroke who started aspirin or clopidogrel for the first time were selected from 2003 to 2010 National Health Insurance Service-National Sample Cohort (NHIS-NSC) of South Korea (n = 4621), a randomly collected sample which accounts for 2.2% (n = 1,017,468) of total population (n = 46,605,433). The prevalence of discontinuation of antiplatelets was measured every 6 months until the 24 months since the first prescription. Then we classified the participants into 2 groups according to the discontinuation status at 12 months and assessed the factors influencing premature discontinuation of antiplatelets within 12 months. RESULTS: Among total participants, 35.5% (n = 1640) discontinued antiplatelets within 12 months and 58.5% (n = 2704) discontinued them within 24 months. The remaining 41.5% (n = 1917) continued them for 24 months or more. In the multivariate logistic regression analysis, initiating treatment with aspirin monotherapy [adjusted OR (aOR), 2.66, 95% CI 2.17-3.25] was the most prominent determinant of premature discontinuation within 12 months followed by CCI score ≥ 6 (aOR 1.50, 95% CI 1.31-1.98), and beginning treatment with clopidogrel monotherapy (aOR 1.41, 95% CI 1.15-1.72). Rural residency (aOR 1.36, 95% CI 1.14-1.62), < 4 total prescribed drugs (aOR 1.24, 95% CI 1.05-1.47), lower income (aOR 1.20, 95% CI 1.03-1.40 for middle income class and OR 1.21, 95% CI 1.02-1.45 for low income class), and ages ≥70 years (aOR 1.15, 95% CI 1.00-1.31) were also significantly associated with premature discontinuation of antiplatelets within 12 months. CONCLUSIONS: The prevalence of premature discontinuation of antiplatelets after ischemic stroke was quite high. Thus, by understanding factors associated with premature discontinuation, a more strategic approach is required for the physicians to improve persistence with antiplatelets.