Association between warfarin use and incidence of ischemic stroke in Japanese hemodialysis patients with chronic sustained atrial fibrillation: a prospective cohort study

Although generally recommended for atrial fibrillation (AF) in the general population, the efficacy and safety of warfarin in hemodialysis patients remains controversial. Warfarin use in hemodialysis patients may confer an additional risk of bleeding that is not appreciated in patients without renal failure because hemodialysis patients have platelet defects and receive anticoagulation agents during dialysis. The incidence of major bleeding was reported to be higher in Japanese AF patients on warfarin therapy compared to patients in other countries, suggesting that racial differences may influence bleeding tendency. Thus, examining risks and benefits of warfarin therapy in Japanese hemodialysis patients with AF is important. In order to determine associations between warfarin use and new ischemic stroke events, major bleeding, and all-cause mortality, a prospective cohort study of 60 Japanese hemodialysis patients with chronic sustained AF was conducted using Cox proportional modeling and propensity score matching. The mean patient age was 68.1 years. During 110 person-years of follow-up, 13 ischemic strokes occurred. After adjusting for CHADS2 score, warfarin use was not associated with a significant reduction in ischemic stroke events [hazard ratio (HR) 3.36; 95 % confidence interval (CI) 0.94-11.23]. Similar results were obtained after propensity score matching (HR 3.36; 95 % CI 0.67-16.66). Warfarin use was not associated with significant increases in major bleeding or all-cause mortality. These results suggest that warfarin may not prevent ischemic stroke in Japanese hemodialysis patients with chronic sustained AF. Adequately powered studies are needed to determine the risks and benefits of anticoagulation therapy in these patients.