How it's calculated
Nine risk factors are each scored 1 point (renal and liver dysfunction, and drugs and alcohol, are scored separately even though grouped under the same letter), for a maximum of 9 points, estimating annual major bleeding risk on anticoagulation.
Score interpretation
| Score | Approximate annual major bleeding risk |
|---|---|
| 0 | 0.9% |
| 1 | 3.4% |
| 2 | 4.1% |
| 3 | 5.8% |
| 4 | 8.9% |
| ≥5 | 9.1% |
Clinical use
- HAS-BLED is used alongside a stroke-risk score (CHA₂DS₂-VASc) — a high bleeding-risk score is not, by itself, a reason to withhold anticoagulation when stroke risk supports it, but it flags patients needing closer monitoring.
- Several HAS-BLED components are modifiable (blood pressure control, avoiding concurrent NSAIDs, achieving stable INR control) — addressing these can meaningfully reduce bleeding risk without abandoning anticoagulation.
- A high HAS-BLED score alongside a high CHA₂DS₂-VASc score usually still favours anticoagulation with closer follow-up, since the absolute stroke risk reduction generally outweighs the bleeding risk increase in this scenario.
- HAS-BLED was derived and validated in patients already on anticoagulation — it estimates bleeding risk in that context, not bleeding risk in general.
Frequently asked questions
What is the HAS-BLED score used for?
It estimates the annual risk of major bleeding in patients with atrial fibrillation who are being considered for, or already on, anticoagulation — used alongside a stroke risk score to inform the overall risk-benefit discussion.
Does a high HAS-BLED score mean anticoagulation should be avoided?
Not necessarily — it flags a patient for closer monitoring and correction of modifiable risk factors (like uncontrolled blood pressure or concurrent NSAID use), but a high stroke risk usually still favours anticoagulation even with an elevated bleeding risk score.
What counts as a 'labile INR'?
An INR that is unstable, often out of the therapeutic range, or with less than 60% time spent in the therapeutic range on warfarin — this criterion doesn't apply to patients on a direct oral anticoagulant (DOAC), which doesn't require INR monitoring.
Can HAS-BLED risk factors be modified?
Yes — several are modifiable, including blood pressure control, avoiding concurrent NSAIDs or antiplatelet agents where possible, and achieving more stable INR control, all of which can reduce bleeding risk without necessarily stopping anticoagulation.
References
- Pisters R, et al. A novel user-friendly score (HAS-BLED) to assess 1-year risk of major bleeding. Chest. 2010;138:1093-1100.
- Hindricks G, et al. 2020 ESC Guidelines for the diagnosis and management of atrial fibrillation. Eur Heart J. 2021;42:373-498.
- Lip GY, et al. Comparative validation of a novel risk score for predicting bleeding risk. J Am Coll Cardiol. 2011;57:173-180.