Abstract
Whether the benefit of dabigatran relative to warfarin is similar in frail and non-frail patients is of great clinical relevance. We conducted a propensity score-matched cohort study of 153,421 Medicare beneficiaries with atrial fibrillation who initiated dabigatran or warfarin in 2010–2014. The outcome was a composite endpoint of death, ischemic stroke, acute myocardial infarction, and major bleeding. Compared with warfarin, dabigatran-treated patients had lower rates, per 1000 person-years, of the composite endpoint (88.7 vs 103.8 events; hazard ratio [HR], 0.89; 95% confidence interval, 0.86–0.93). The advantage of dabigatran diminished with increasing levels of frailty: HRs for mild, moderate and severe frailty were 0.71, 0.85 and 1.02, respectively. This was driven by the greater benefit of dabigatran for major bleeding in patients with less frailty: the corresponding HRs were 0.65, 0.83 and 1.05, respectively. Our results suggest that dabigatran was not more effective or safer than warfarin in severely frail patients.