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.


RESULTS
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.
Divisions of Clinical Epidemiology and General Internal Medicine, McGill University Health Center, Montreal, Quebec, Canada (M.S., M.A.T., NE.R., H.B., L.P._; Department of Pharmacy Practice and Administration, College of Pharmacy, Western University of Health Sciences, Pomona, CA (C.A.J.); Division of Cardiology, McGill University Health Center, Montreal, Quebec, Canada (V.E.); Divisions of Cardiology and Clinical Epidemiology, Jewish General Hospital/McGill University, Montreal, Quebec, Canada (M.J.E.); Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada (K.H.H.); Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada; Institute of Health Policy, Management and Evaluation, Faculty of Medicine, University of Toronto, Toronto, Canada; Division of Cardiology, Schulich Heart Centre, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Canada (J.V.T.); and Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada (H.G.).
Mitesh
M
Shah
Meytal
M
Avgil Tsadok
Cynthia A
CA
Jackevicius
Vidal
V
Essebag
Mark J
MJ
Eisenberg
Elham
E
Rahme
Karin H
KH
Humphries
Jack V
JV
Tu
Hassan
H
Behlouli
Helen
H
Guo
Louise
L
Pilote
D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000009:adverse effects; D001281:Atrial Fibrillation / Q000453:epidemiology* / Q000628:therapy; D015331:Cohort Studies; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced / Q000453:epidemiology*; D006801:Humans; D008297:Male; D009864:Ontario / Q000453:epidemiology; D011159:Population Surveillance / Q000379:methods; D011792:Quebec / Q000453:epidemiology; D006435:Renal Dialysis / Q000009:adverse effects; D012189:Retrospective Studies; D012307:Risk Factors; D020521:Stroke / Q000139:chemically induced / Q000453:epidemiology*; D014859:Warfarin / Q000009:adverse effects*
D000925:Anticoagulants; D014859:Warfarin
atrial fibrillation; dialysis; hemorrhage; stroke; warfarin