Calculate the HAS-BLED score to estimate 1-year major bleeding risk in atrial fibrillation patients on anticoagulation and flag modifiable risk factors.
HAS-BLED Score Formula
The HAS-BLED score is the sum of one point for each risk factor that is present. Two of the letters cover two factors each, so they can contribute up to two points.
HAS-BLED = H + A + S + B + L + E + D
- H = Hypertension, uncontrolled with systolic blood pressure over 160 mmHg (1 point)
- A = Abnormal renal function (1 point) plus abnormal liver function (1 point), so 0 to 2 points
- S = Stroke history (1 point)
- B = Bleeding history or predisposition, such as prior major bleeding or anemia (1 point)
- L = Labile INR, meaning time in therapeutic range under 60 percent on warfarin (1 point)
- E = Elderly, age over 65 years (1 point)
- D = Drugs that raise bleeding risk (1 point) plus alcohol use of 8 or more drinks per week (1 point), so 0 to 2 points
Each box you check in score mode adds its points to the running total, which ranges from 0 to 9. The total is then read against the published bleeding rate to place the patient in a low, moderate, or high risk group. Lookup mode skips the checklist: you enter a score you already have and it returns the same bleeding rate and category. A score of 3 or more is the accepted cutoff for high risk.
Bleeding Risk by Score and Which Factors You Can Change
The first table lists the one-year major bleeding rate for each score from the original validation study. Rates for scores of 6 and above are not shown because too few patients reached them to give a stable estimate.
| HAS-BLED score | Major bleeds per 100 patient-years | Risk group |
|---|---|---|
| 0 | 1.13 | Low |
| 1 | 1.02 | Moderate |
| 2 | 1.88 | Moderate |
| 3 | 3.74 | High |
| 4 | 8.70 | High |
| 5 | 12.50 | High |
The point of the score is not to withhold anticoagulation but to find risk that can be reduced. The next table marks which factors are modifiable and the action that lowers each one. This is the part clinicians act on after the score is known.
| Factor | Modifiable | Action that lowers risk |
|---|---|---|
| Hypertension | Yes | Control blood pressure to systolic below 140 mmHg |
| Bleeding predisposition | Often | Find and treat the bleeding source and correct anemia |
| Labile INR | Yes | Improve time in therapeutic range or switch to a DOAC |
| Drugs (antiplatelet, NSAID) | Yes | Stop NSAIDs and avoid unnecessary antiplatelet therapy |
| Alcohol use | Yes | Reduce intake to under 8 drinks per week |
| Abnormal renal function | No | Manage the underlying kidney disease |
| Abnormal liver function | No | Manage the underlying liver disease |
| Stroke history | No | Fixed; weigh against stroke prevention benefit |
| Elderly (over 65) | No | Fixed; supports closer monitoring |
Example Problems
Example 1. A 72-year-old with uncontrolled hypertension who takes daily aspirin. That is one point for elderly, one for hypertension, and one for a drug that raises bleeding risk, for a total of 3. The score falls in the high risk group at about 3.74 major bleeds per 100 patient-years. Two of the three factors are modifiable: control the blood pressure and review whether the aspirin is still needed.
Example 2. A 60-year-old on warfarin with a prior stroke and a time in therapeutic range of 50 percent. That is one point for stroke history and one for labile INR, for a total of 2, which is the moderate group at about 1.88 major bleeds per 100 patient-years. The labile INR is the modifiable factor, so improving INR control or switching to a DOAC is the lever that lowers the risk.
Frequently Asked Questions
What counts as a high HAS-BLED score? A score of 3 or more is high risk. It flags a patient who needs regular review after starting anticoagulation and whose reversible risk factors should be corrected. It does not by itself mean the patient cannot receive an anticoagulant.
Does a high score mean I should stop the anticoagulant? No. The score was designed to identify and address bleeding risk, not to rule out treatment. Most patients with atrial fibrillation still benefit from anticoagulation because it prevents stroke. Weigh the HAS-BLED result against the stroke risk from the CHA2DS2-VASc score, then reduce the modifiable factors.
How is labile INR defined? Labile INR applies to patients on warfarin whose time in therapeutic range is under 60 percent, or who have frequent high or unstable readings. It does not apply to patients on a direct oral anticoagulant, since those drugs are not monitored with the INR.