This calculator is for general information and education. It is not medical advice and does not replace the judgment of a doctor, nurse or pharmacist who knows the full clinical picture.
Blood thinners prevent most strokes in atrial fibrillation, but they also cause bleeding. Doctors weigh the two risks before and during treatment. The ATRIA bleeding score, published by Fang and colleagues in 2011 from the Anticoagulation and Risk Factors in Atrial Fibrillation study of about 9,000 patients on warfarin in California, estimates the yearly risk of major bleeding.
The score
| Risk factor | Points |
|---|---|
| Anemia (hemoglobin under 13 g/dL in men, under 12 g/dL in women) | 3 |
| Severe kidney disease (eGFR under 30 mL/min or dialysis) | 3 |
| Age 75 or older | 2 |
| Any prior hemorrhage | 1 |
| Diagnosed hypertension | 1 |
The total ranges from 0 to 10.
Example
A 78-year-old with treated hypertension, no anemia, normal kidney function and no history of bleeding scores 2 + 1 = 3: low risk.
Interpretation
| ATRIA | Risk group | Major bleeding per year |
|---|---|---|
| 0 to 3 | low | about 0.8% |
| 4 | intermediate | about 2.6% |
| 5 to 10 | high | about 5.8% |
Major bleeding meant fatal bleeding, bleeding needing transfusion of two units or more, or bleeding into a critical site such as the brain.
ATRIA, HAS-BLED and HEMORR₂HAGES
The three scores share most risk factors. HAS-BLED is the one recommended by European guidelines, partly because it highlights factors that can be corrected, such as uncontrolled blood pressure, unstable INR, alcohol and aspirin or NSAIDs. ATRIA gives more weight to anemia and kidney disease.
How to use the result
A high bleeding score is rarely a reason to stop anticoagulation on its own, because the stroke risk usually outweighs it. It is a reason to:
- treat what can be treated (blood pressure, anemia, alcohol, interacting drugs);
- prefer a direct oral anticoagulant over warfarin when appropriate, as it causes fewer brain bleeds;
- follow up more often.
Never stop a blood thinner without talking to your doctor.