Evaluation of the HAS-BLED, ATRIA and ORBIT bleeding risk scores in atrial fibrillation patients on warfarin

INTRODUCTION: Various bleeding risk prediction schemes, such as the HAS-BLED, ATRIA and ORBIT scores have been proposed in patients with atrial fibrillation (AF). We compared the relative predictive values of these bleeding risk scores for clinically relevant bleeding, as well as the relationship of ATRIA and ORBIT scores to the quality of anticoagulation control on warfarin, as reflected by time in therapeutic range (TTR).

METHODS: A post-hoc ancillary analysis of 'clinically relevant bleeding' and 'major bleeding' events amongst 2293 patients on warfarin therapy in the AMADEUS trial.

RESULTS: Only HAS-BLED was significantly predictive for clinically relevant bleeding, and all 3 risk scores were predictive for major bleeding. The predictive performance of HAS-BLED was modest, as reflected by c-indexes of 0.59 (p<0.001) and 0.65 (p<0.002), for clinically relevant bleeding and major bleeding, respectively. The HAS-BLED score performed better than ATRIA (P=0.002) or ORBIT (P=0.001) in predicting any clinically relevant bleeding. Only the HAS-BLED score was significantly associated with the risk for both bleeding outcomes on Cox regression analysis (any clinically relevant bleeding; hazard ratio [HR] 1.85, 95%CI 1.43-2.40, p<0.001, and major bleeding; HR 2.40, 95%CI 1.28-4.52, p=0.007). There were strong inverse correlations of ATRIA and ORBIT scores to TTR as a continuous variable ('low risk' ATRIA, r= -0.96; P=0.003; ORBIT, r= -0.96; p=0.003). Improvement in the predictive performance for both ATRIA and ORBIT scores for any clinically relevant bleeding was achieved by adding TTR to both scores, with significant differences in c-indexes (p=0.001 and p=0.002, respectively), NRI and IDI (both p<0.001).

CONCLUSION: All three bleeding risk prediction scores demonstrated modest predictive ability for bleeding outcomes, although the HAS-BLED score performed better than either the ATRIA or ORBIT scores. Significant improvements in both ATRIA and ORBIT score prediction performances were achieved by adding TTR to both scores.