We conducted a population-based retrospective cohort study of patients aged ≥65 years 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 nondialysis 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 nondialysis patients. The cohort comprised 1626 dialysis patients and 204 210 nondialysis patients. Among dialysis patients, 46% (756/1626) patients were prescribed
warfarin. Among dialysis patients,
warfarin users had more
congestive heart failure and
diabetes mellitus, but fewer prior
bleeding events in comparison with the no-
warfarin users. Among dialysis patients,
warfarin use, in comparison with no-
warfarin use, was not associated with a lower risk for
stroke (adjusted hazard ratio, 1.14; 95% confidence interval, 0.78-1.67) but was associated with a 44% higher risk for
bleeding (adjusted hazard ratio, 1.44; 95% confidence interval, 1.13-1.85) after adjusting for potential confounders. Propensity score-adjusted analyses yielded similar results.
CONCLUSIONS: Our results suggest that
warfarin use is not beneficial in reducing
stroke risk, but it is associated with a higher
bleeding risk in patients with AF undergoing dialysis.