Assessment of Outcomes of Treatment With Oral Anticoagulants in Patients With Atrial Fibrillation and Multiple Chronic Conditions: A Comparative Effectiveness Analysis

IMPORTANCE: Comparative effectiveness and safety of oral anticoagulants in patients with atrial fibrillation (AF) and multiple chronic conditions (MCC) are unknown. OBJECTIVE: To determine whether there are differences in efficacy and safety of dabigatran, rivaroxaban, and warfarin regarding stroke prevention and bleeding rates, respectively, in elderly patients with AF with MCC. DESIGN, SETTING, AND PARTICIPANTS: This retrospective comparative effectiveness analysis included data from the population-based Medicare beneficiaries database, evaluating patients with new AF diagnosed from January 1, 2010, to December 31, 2013, who initiated an oral anticoagulant within 90 days of diagnosis. Patients with CHA(2)DS(2)-VASc scores of 1 to 3, 4 to 5, and 6 or higher; HAS-BLED scores of 0 to 1, 2, and 3 or higher; and Gagne comorbidity scores of 0 to 2, 3 to 4, and 5 or higher were categorized as having low, moderate, or high morbidity, respectively. Within morbidity categories, patients receiving dabigatran, rivaroxaban, or warfarin were matched using a 3-way propensity matching, and the relative hazards of stroke, major hemorrhage (MH), and death were evaluated. Data analysis included follow-up from the date of initial anticoagulant use through December 31, 2013. EXPOSURES: Rivaroxaban (20 mg once daily), dabigatran (150 mg twice daily), or warfarin therapy. MAIN OUTCOMES AND MEASURES: Ischemic stroke, MH, and death. RESULTS: The study cohort included 21 979 patients using dabigatran (mean [SD] age, 75.8 [6.4] years; 51.1% female), 23 177 using rivaroxaban (mean [SD] age, 75.8 [6.4] years; 49.9% female), and 101 715 using warfarin (mean [SD] age, 78.5 [7.2] years; 57.3% female). In the propensity-matched cohorts, there were no differences in stroke rates between the 3 oral anticoagulant groups. Dabigatran users had lower hazard of MH compared with warfarin users among patients with low MCC (hazard ratio [HR], 0.62; 95% CI, 0.47-0.83; P < .001; for MCC defined as low CHA(2)DS(2)-VASc score), and similar risk in patients with moderate to high MCC. While there was no difference in MH between rivaroxaban and warfarin users, rivaroxaban users had significantly higher MH risk compared with dabigatran users in the medium and high comorbidity groups (HR, 1.24; 95% CI, 1.04-1.48; P = .02 and HR, 1.28; 95% CI, 1.05-1.56; P = .01, respectively). Dabigatran and rivaroxaban users had lower rates of death compared with warfarin users (HR ranged from 0.52-0.84), across comorbidity levels. CONCLUSIONS AND RELEVANCE: Oral anticoagulants are similarly effective in stroke prevention among patients with AF with MCC. However, dabigatran and rivaroxaban use may be associated with lower rates of mortality in patients with MCC.