Quantifying Bleeding Risk in Atrial Fibrillation
The HAS-BLED score is the recommended tool for bleeding risk assessment in patients with atrial fibrillation, as it outperforms other bleeding risk scores in predicting serious bleeding events while also helping identify modifiable risk factors. 1
Major Bleeding Risk Assessment Tools
Several validated bleeding risk scores have been developed specifically for atrial fibrillation patients:
HAS-BLED Score
The most widely recommended score includes:
- Hypertension (uncontrolled, >160 mmHg systolic) - 1 point
- Abnormal renal/liver function (1 point each) - 1-2 points
- Stroke history - 1 point
- Bleeding history or predisposition - 1 point
- Labile INR (if on warfarin) - 1 point
- Elderly (>65 years) - 1 point
- Drugs/alcohol concomitantly (1 point each) - 1-2 points
A score ≥3 indicates high bleeding risk 1
Other Validated Bleeding Risk Scores
- HEMORR₂HAGES: Hepatic/renal disease, Ethanol abuse, Malignancy, Older age, Reduced platelet count/function, Rebleeding risk, Hypertension, Anemia, Genetic factors, Excessive fall risk, Stroke
- ATRIA: Anemia, severe renal disease, age ≥75, prior hemorrhage, hypertension
- ORBIT: Older age (≥75), Reduced hemoglobin/hematocrit/anemia, Bleeding history, Insufficient kidney function, Treatment with antiplatelets 1, 2
- ABC-bleeding: Age, biomarkers, clinical history 1
Clinical Application of Bleeding Risk Assessment
When to Use Bleeding Risk Scores
Bleeding risk assessment should be performed in all patients with AF at every patient contact 1. The primary purpose is to:
- Identify modifiable bleeding risk factors
- Flag high-risk patients (HAS-BLED ≥3) who need more frequent follow-up and monitoring
- Guide clinical decision-making regarding anticoagulation therapy
Interpreting HAS-BLED Results
- Score 0-2: Low-moderate bleeding risk
- Score ≥3: High bleeding risk requiring more frequent review and follow-up (every 4 weeks rather than every 4-6 months) 1
Important Considerations
A high bleeding risk score is NOT a reason to withhold oral anticoagulation 1. The net clinical benefit of stroke prevention is often greater in those with high bleeding risk.
Bleeding risk is dynamic and requires regular reassessment 1.
Modifiable risk factors should be addressed:
- Uncontrolled hypertension
- Labile INRs (if on warfarin)
- Concomitant medications (NSAIDs, antiplatelet drugs)
- Excessive alcohol consumption
- Correctable anemia or thrombocytopenia
- Reversible renal or hepatic dysfunction 1
Performance of Bleeding Risk Scores
The HAS-BLED score has demonstrated superior performance compared to other scores:
- Outperforms CHADS₂ and CHA₂DS₂-VASc for predicting serious bleeding 1
- Shows better discrimination than HEMORR₂HAGES and ATRIA 1
- Demonstrates significant improvement in net reclassification compared to other scores 3
- Is the only score predictive of intracranial bleeding 1
However, all bleeding risk scores have modest predictive ability with c-statistics around 0.6-0.7 1, 2.
Relationship Between Stroke and Bleeding Risk
An important clinical observation is that stroke risk and bleeding risk often correlate with each other 1, 4. Patients at high risk of bleeding (HAS-BLED ≥3) are often also at high risk of stroke/thromboembolism 3.
The HAS-BLED score has shown predictive value not only for bleeding but also for cardiovascular events and mortality 4, highlighting the complex relationship between thrombosis and bleeding.
Practical Application in Clinical Decision-Making
- Calculate both stroke risk (CHA₂DS₂-VASc) and bleeding risk (HAS-BLED)
- Address modifiable bleeding risk factors regardless of whether anticoagulation is prescribed
- Schedule more frequent follow-up for patients with HAS-BLED ≥3
- Consider NOAC dose adjustments based on bleeding risk:
Remember that the goal of bleeding risk assessment is not to avoid anticoagulation but to identify and mitigate modifiable risk factors while ensuring appropriate monitoring and follow-up.