Warfarin use and the risk for stroke and bleeding in patients with atrial fibrillation undergoing dialysis

Background — Current observational studies on warfarin use and the risk for stroke and bleeding in patients with atrial fibrillation (AF) undergoing dialysis found conflicting results.

Methods and Results — The authors conducted a population-based retrospective cohort study of patients aged 65 years and older admitted to a hospital with a primary or secondary diagnosis of AF, in Quebec and Ontario, Canada from 1998 to 2007. The AF cohort was grouped into dialysis (hemodialysis and peritoneal dialysis) and non-dialysis patients and into warfarin and no-warfarin users according to the first prescription filled for warfarin within 30 days after AF hospital discharge. We determined the association between warfarin use and the risk for stroke and bleeding in dialysis and non-dialysis patients. The cohort was comprised of 1,626 dialysis patients and 204,210 non-dialysis patients. Among dialysis patients, 46% (756/1,626) patients were prescribed warfarin. Among dialysis patients, warfarin users had more congestive heart failure and diabetes but less prior bleeding event compared to the no-warfarin users. Among dialysis patients, warfarin use, compared to no-warfarin use, was not associated with a lower risk for stroke (adjusted hazard ratio (HR): 1.14, 95% confidence interval (CI): 0.78 to 1.67) but was associated with a 44% higher risk for bleeding (adjusted HR: 1.44, 95% CI: 1.13 to 1.85) after adjusting for potential confounders. Propensity score adjusted analyses yielded similar results.

Conclusions — Results suggest that warfarin use is not beneficial in reducing stroke risk but is associated with a higher bleeding risk in patients with AF undergoing dialysis.