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Net Clinical Benefit of Warfarin in Patients With Atrial Fibrillation: A Report From the Swedish Atrial Fibrillation Cohort Study
Study Questions:
What is the risk:benefit ratio of warfarin in patients with atrial fibrillation (AF)?
Methods:
The data in this study were obtained from a national database that included 170,292 patients (mean age 76 years) with a diagnosis of AF in 2005-2008. Fifty-three percent of patients were not treated with warfarin. The mean duration of follow-up was 1.5 years. Net clinical benefit (NCB) was defined as the number of ischemic strokes off warfarin minus the number of intracranial hemorrhages on warfarin with a weight of 1.5 to account for the more severe consequences of intracranial hemorrhage. NCBs were analyzed according to stroke risk (CHA2DS2-VASc score) and bleeding risk (HAS-BLED score).
Results:
The NCB favored warfarin for patients with a CHA2DS2-VASc score ≥1. The greatest NCB occurred in patients with the highest risk scores. The adjusted NCB was >6%/year in patients with a CHA2DS2-VASc score of 6 and a HAS-BLED score of 4. In the small subgroup of patients with a CHA2DS2-VASc score of 0 and moderately elevated bleeding risk, the NCB did not favor warfarin.
Conclusions:
The authors concluded that the risk of ischemic stroke off warfarin exceeds the risk of intracranial hemorrhage on warfarin for almost all patients with AF.
Perspective:
Of note is that the risk of intracranial bleeding on warfarin exceeded the risk of ischemic stroke off warfarin in only 0.4% of patients in this very large AF cohort. The data indicate that almost all patients with AF have more to gain than to lose from anticoagulation with warfarin.
Keywords: Odds Ratio, Stroke, Intracranial Hemorrhages, Follow-Up Studies, Warfarin, Atrial Fibrillation, Risk Assessment
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