Warfarin Use in Patients with Atrial Fibrillation Undergoing Hemodialysis: A Nationwide Population-Based Study

Background and Purpose - The aim of this study is to elucidate the effects of warfarin use in patients with atrial fibrillation undergoing dialysis using a population-based Korean registry. Methods - Data were extracted from the Health Insurance Review and Assessment Service, which is a nationwide, mandatory social insurance database of all Korean citizens enrolled in the National Health Information Service between 2009 and 2013. Thromboembolic and hemorrhagic outcomes were analyzed according to warfarin use. Overall and propensity score-matched cohorts were analyzed by Cox proportional hazards models. Results - Among 9974 hemodialysis patients with atrial fibrillation, the mean age was 66.6±12.2 years, 5806 (58.2%) were men, and 2921 (29.3%) used warfarin. After propensity score matching to adjust for all described baseline differences, 5548 subjects remained, and differences in baseline variables were distributed equally between warfarin users and nonusers. During a mean follow-up duration of 15.9±11.1 months, ischemic and hemorrhagic stroke occurred in 678 (6.8%) and 227 (2.3%) patients, respectively. In a multiple Cox model, warfarin use was significantly associated with an increased risk of hemorrhagic stroke (hazard ratio, 1.44; 95% confidence interval, 1.09-1.91; P=0.010) in the overall cohort. Furthermore, a significant relationship between warfarin use and hemorrhagic stroke was found in propensity-matched subjects (hazard ratio, 1.56; 95% confidence interval, 1.10-2.22; P=0.013). However, the ratios for ischemic stroke were not significantly different in either the propensity-matched (hazard ratio, 0.95; 95% confidence interval, 0.78-1.15; P=0.569) or overall cohort (hazard ratio, 1.06; 95% confidence interval, 0.90-1.26; P=0.470). Conclusions - Our findings suggest that warfarin should be used carefully in hemodialysis patients, given the higher risk of hemorrhagic events and the lack of ability to prevent thromboembolic complications.