Background: Thromboembolic and bleeding risk are elevated in older patients with atrial fibrillation and prior stroke. We compared dabigatran with rivaroxaban for secondary prevention in a national population after skilled nursing facility (SNF) discharge.
Methods: Medicare fee-for-service beneficiaries aged ≥ 65 years with atrial fibrillation hospitalized for ischemic stroke (November 2011-October 2013) and subsequently admitted to an SNF were studied. Dabigatran (n = 332) and rivaroxaban users (n = 378) were compared in a retrospective, active comparator, new-user cohort. The index medication claim occurred within 120 days after hospital discharge and exposure continued until a 14-day treatment gap ('as treated'). The primary net clinical benefit outcome was the time to recurrent stroke, transient ischemic attack, intracranial hemorrhage, extracranial bleed, myocardial infarction, venous thromboembolism, or death. All-cause mortality was evaluated separately as a secondary outcome. Multivariable adjusted Cox models stratified by dosage estimated hazard ratios (aHR).
Results: Among those receiving low dosages, the crude composite event rate was 40.4/100 person-years among dabigatran users and 33.7/100 person-years among rivaroxaban users. The composite outcome [aHR 1.48; 95% confidence interval (CI) 0.87-2.51] and all-cause mortality (aHR 1.67; 95% CI 0.84-3.31) rates were higher among low-dose dabigatran users. For those receiving standard doses, the crude composite event rates were 19.5/100 person-years for dabigatran users and 37.1/100 person-years for rivaroxaban users. Although no difference in mortality was observed, the composite outcome rate was lower among standard-dose dabigatran users (aHR 0.65; 95% CI 0.36-1.15).
Conclusions: In older adults treated with direct-acting oral anticoagulants after ischemic stroke, outcome rates varied considerably by drug and dosage.