Evaluation of the Age, Biomarkers, and Clinical History–Bleeding Risk Score in Patients With Atrial Fibrillation With Combined Aspirin and Anticoagulation Therapy Enrolled in the ARISTOTLE and RE-LY Trials

IMPORTANCE: Most patients with atrial fibrillation (AF) and coronary artery disease have indications for preventing stroke with oral anticoagulation therapy and preventing myocardial infarction and stent thrombosis with platelet inhibition. OBJECTIVE: To evaluate whether the recently developed ABC (age, biomarkers, and clinical history)–bleeding risk score might be useful to identify patients with AF with different risks of bleeding during concomitant aspirin and anticoagulation therapy. DESIGN, SETTING, AND PARTICIPANTS: The biomarkers in the ABC-bleeding risk score (growth differentiation factor 15, hemoglobin, and troponin) were measured in blood samples collected at randomization between 2006 and 2010 in the ARISTOTLE (Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation) trial and between 2005 and 2009 in the RE-LY (Randomized Evaluation of Long-term Anticoagulation Therapy) trial, both of which were multinational randomized clinical trials. The trials were reported 2011 and 2009, respectively. A total of 24 349 patients with AF (14 980 patients from the ARISTOTLE trial and 9369 patients from the RE-LY trial) were analyzed in the present cohort study. The median (interquartile range) length of follow-up was 1.8 (1.3-2.3) years in the ARISTOTLE cohort and 2.0 (1.6-2.3) years in the RE-LY cohort. Data analysis was performed from February 2018 to June 2019. EXPOSURES: Concomitant aspirin treatment during study follow-up. MAIN OUTCOMES AND MEASURES: Time to first occurrence of a major bleeding was determined according to International Society on Thrombosis and Hemostasis definition. Hazard ratios were estimated with Cox models adjusted for ABC-bleeding risk score and randomized treatment. RESULTS: The median (interquartile range) age was 70 (63-76) years in the ARISTOTLE cohort and 72 (67-77) years in the RE-LY cohort (5238 patients [35.6%] in the ARISTOTLE cohort and 3086 patients [36.4%] in the RE-LY cohort were women). The total number of patients with a first major bleeding event was 651 (207 with aspirin and 444 without) in ARISTOTLE and 463 (238 with aspirin and 225 without) in RE-LY. For both cohorts, in those with a low ABC-bleeding risk score, the absolute bleeding rate was low even with concomitant aspirin treatment, whereas in those with a higher ABC-bleeding risk score, the rate of bleeding was higher with concomitant aspirin compared with oral anticoagulation alone (ARISTOTLE, hazard ratio, 1.65; 95% CI, 1.40-1.95; P < .001; RE-LY, hazard ratio, 1.70; 95% CI, 1.42-2.04; P < .001). Thus, a low annual ABC-bleeding risk (eg, 0.5% without aspirin use) would with concomitant aspirin result in an annual rate of 0.8%, and a high estimated ABC-bleeding risk (eg, 3.0%) would result in a substantially higher rate of 5.0%. CONCLUSIONS AND RELEVANCE: These findings suggest that the ABC-bleeding risk score identifies patients with different risks of bleeding when combining aspirin and oral anticoagulation. The ABC-bleeding risk score may, therefore, be a useful tool for decision support concerning intensity and duration of combination antithrombotic treatment in patients with AF and coronary artery disease.