BACKGROUND: Various bleeding risk scores have been proposed to assess the risk 
of bleeding in patients with atrial fibrillation taking oral anticoagulants. 
Limited data are available with these scores, in users of non-vitamin K 
antagonist oral anticoagulants.
METHODS: Using the Danish registries, we evaluated and compared the risk 
classification properties of the Hypertension, Age, Stroke, Bleeding 
tendency/predisposition, Labile international normalized ratios, Elderly 
age/frailty, Drugs such as concomitant aspirin/nonsteroidal anti-inflammatory 
drugs or alcohol excess (HAS-BLED), Anticoagulation and Risk Factors in Atrial 
Fibrillation (ATRIA), and Outcomes Registry for Better Informed Treatment of 
Atrial Fibrillation (ORBIT) scores for predicting major bleeding in 57,930 
atrial fibrillation patients (44.6% female; mean age 73.5 years, standard 
deviation 11.4 years; mean CHA2DS2-VASc score 3.2, standard deviation 1.8).
RESULTS: At 1-year follow-up, C-statistics for ATRIA, HAS-BLED, and ORBIT were 
approximately 0.59, with only minor differences between scores. Both ATRIA and 
ORBIT categorized more patients as "low risk" (both >83%, when compared with 
HAS-BLED, only 53%), and qualitatively, the receiver operating characteristic 
curves revealed higher sensitivity (62.8%) for HAS-BLED compared with ATRIA 
(29.7%) and ORBIT (37.1%). The clinical usefulness of scores was evaluated using 
decision curve analyses at a 1-year perspective. If the intervention threshold 
is low (<1.7%), the benefit is toward monitoring all patients. If preference is 
for a major bleeding risk threshold between 1.7% and 2.0%, most benefit was 
obtained by using HAS-BLED. The ORBIT and ATRIA scores provided better benefit 
for thresholds between 2.0% and 6.0%.
CONCLUSION: This analysis of contemporary bleeding risk score stratification in 
a "real-world" non-vitamin K antagonist oral anticoagulant users population with 
atrial fibrillation showed modest predictive values using C-statistics. The 
scores represent different risk thresholds, with HAS-BLED classifying least 
patients at low risk and achieving the highest benefit if applying a major 
bleeding intervention threshold of approximately 2%, whereas benefit from using 
either ATRIA score or ORBIT score was only evident using higher intervention 
thresholds.