WHAT IS KNOWN AND OBJECTIVE: Bleeding risk scores (BRSs) aid in the assessment 
of oral anticoagulant-related bleeding risk in patients with atrial 
fibrillation. Ideally, the applicability of a BRS needs to be assessed, prior to 
its routine use in a population other than the original derivation cohort. 
Therefore, we evaluated the performance of 6 established BRSs to predict major 
or clinically relevant bleeding (CRB) events associated with the use of oral 
anticoagulant (OAC) among Malaysian patients.
METHODS: The pharmacy supply database and the medical records of patients with 
non-valvular atrial fibrillation (NVAF) receiving warfarin, dabigatran or 
rivaroxaban at two tertiary hospitals were reviewed. Patients who experienced an 
OAC-associated major or CRB event within 12 months of follow-up, or who have 
received OAC therapy for at least 1 year, were identified. The BRSs were fitted 
separately into patient data. The discrimination and the calibration of these 
BRSs as well as the factors associated with bleeding events were then assessed.
RESULTS: A total of 1017 patients with at least 1-year follow-up period, or 
those who developed a bleeding event within 1 year of OAC use, were recruited. 
Of which, 23 patients experienced a first major bleeding event, whereas 76 
patients, a first CRB event. Multivariate logistic regression results show that 
age of 75 or older, prior bleeding and male gender are associated with major 
bleeding events. On the other hand, prior gastrointestinal bleeding, a 
haematocrit value of less than 30% and renal impairment are independent 
predictors of CRB events. All the BRSs show a satisfactory calibration for major 
and CRB events. Among these BRSs, only HEMORR2 HAGES (C-statistic = 0.71, 95% CI 
0.60-0.82, P < .001) and ATRIA score (C-statistic = 0.70, 95% CI 0.58-0.82, 
P < .001) show acceptable discrimination performance for major bleeding events. 
All the 6 BRSs, however, lack acceptable predictive performance for CRB events.
WHAT IS NEW AND CONCLUSION: To the best of our knowledge, this is the first 
evaluation study of the predictive performance of these 6 BRSs on clinically 
relevant bleeding events applied to the same cohort consisting of mainly Asian 
novel oral anticoagulant users. These BRSs show poor to acceptable predictive 
performance on OAC-induced major or CRB events. An improvement in the existing 
BRSs for OAC users is warranted.