HAS-BLED Bleeding Risk Calculator

Understanding the HAS-BLED score calculator — concept and principle

HAS-BLED estimates the one-year risk of major bleeding in people with atrial fibrillation who take, or are being considered for, oral anticoagulation. It flags patients who need closer follow-up and points out correctable risks such as uncontrolled blood pressure, unnecessary antiplatelet drugs or heavy drinking.

The score points to bleeding risks worth fixing, not a verdict on its own.

How it is calculated

Each item scores 1 point when present, for a total of 0 to 9:

H hypertension: uncontrolled, systolic blood pressure above 160 mmHg
A abnormal renal function (for example dialysis, transplant or markedly raised creatinine): 1
A abnormal liver function (for example cirrhosis or markedly abnormal liver tests): 1
S prior stroke: 1
B bleeding history or predisposition, such as anaemia: 1
L labile INR, meaning unstable or often out-of-range INR on a vitamin K antagonist: 1
E elderly, age over 65: 1
D drugs: antiplatelet agents or NSAIDs: 1
D alcohol: about 8 or more drinks per week: 1

The principle

Pisters and colleagues (2010) derived the score from the Euro Heart Survey on AF by testing which clinical features were independently associated with major bleeding during one year. Each selected factor received equal weight to keep the score easy to use at the bedside. Several items, including blood pressure, labile INR, drugs and alcohol, are modifiable. That is the key idea: the score is meant to prompt action on these factors and closer monitoring, not to decide on its own that a patient should go without stroke prevention.

Worked example

Defaults: every item is No.
HAS-BLED = 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 = 0.
Because 0 is below 3, the risk band is low–moderate.
For comparison, a 72-year-old taking an NSAID with uncontrolled hypertension scores 1 + 1 + 1 = 3, the high-risk band.

How to read the result

Where does your result fall?

A score of 0–2 is usually described as low to moderate risk; 3 or more marks high bleeding risk. A high score means correcting modifiable factors and reviewing the patient more often. It is not, by itself, a reason to withhold anticoagulation, because in many patients the stroke prevented outweighs the bleeding risk.

Common mistakes

Using a high HAS-BLED score alone to stop or avoid anticoagulation.
Counting controlled hypertension; the item is for uncontrolled blood pressure.
Scoring labile INR in a patient on a direct oral anticoagulant, where INR is not used for monitoring.

Keep in mind: For information and education only — not a diagnosis or treatment advice. The definitions of renal, liver and bleeding items need clinical judgement. Clinical decisions must be made by a qualified professional.

Frequently asked questions

Is HAS-BLED used with direct oral anticoagulants?

Yes, it is still used to identify bleeding risk factors, but the labile INR item generally does not apply.

Should HAS-BLED be compared with CHA₂DS₂-VASc?

The two scores answer different questions. They are considered together, but a higher bleeding score does not cancel the stroke score.

Sources: Pisters R. et al., Chest, 2010 (derivation of HAS-BLED) · Van Gelder I. C. et al., 2024 ESC Guidelines for the management of atrial fibrillation, European Heart Journal, 2024

Checked 8 Nov 2026. Pisters et al., Chest 2010.

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