Efficacy of DOACs vs. warfarin in high-risk atrial fibrillation patients


Background: DOACs have been shown to be efficacious in randomized, controlled trials, but these trials did not include high-risk patients. This trial studies the efficacy and safety of DOACs in elderly patients with new-onset atrial fibrillation who are at high risk of both ischemic stroke and major bleeding.

Study design: Retrospective comparative effectiveness analysis.

Setting: Data from a population-­based Medicare beneficiaries database.

Synopsis: Data from 213,705 Medicare beneficiaries with new-onset atrial fibrillation on rivaroxaban, dabigatran, or warfarin were analyzed. The investigators calculated CHA2DS2-VASc, HAS-BLED, and Gagne Index comorbidity scores for each participant to assess comorbidity burden and categorize patients into low-, medium-, and high-morbidity categories.

Researchers then used three-way propensity matching, accounting for each morbidity category and anticoagulation medication to compare outcomes. Cox proportion regression models were used to adjust for risk and compare outcomes of ischemic stroke and major hemorrhage in matched participants in each anticoagulant group.

Primary outcomes of the study were ischemic stroke and major hemorrhage, which were determined based on ICD-9 codes. The investigators did not find a significant difference among anticoagulants regardless of the morbidity level for risk-adjusted ischemic stroke rates. Participants in the dabigatran group had lower rates of risk-adjusted major hemorrhage, compared with the warfarin group, regardless of morbidity category. The dabigatran group also had lower major hemorrhage risk, compared with the rivaroxaban group, especially in moderate- and high-morbidity category. Lastly, risk-adjusted rates of mortality were lower in the dabigatran and rivaroxaban groups, compared with the warfarin group, and there was no difference between the dabigatran and rivaroxaban groups with regards to mortality.

Bottom line: Rivaroxaban and dabigatran are each equally effective, compared with warfarin, in preventing ischemic strokes in elderly patients with new-onset atrial fibrillation and multiple comorbidities. However, patients on dabigatran appear to be at less risk of major bleeding, compared with warfarin and rivaroxaban.

Citation: Mentias A et al. Assessment of outcomes of treatment with oral anticoagulants in patients with atrial fibrillation and multiple chronic conditions. JAMA Netw Open. 2018 Sep 28;1(5):e182870.

Dr. Puri is assistant professor of medicine at Northwestern University Feinberg School of Medicine and a hospitalist at Northwestern Memorial Hospital, both in Chicago.

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