HAS-BLED Calculator

Created by Aleksandra Zając, MD
Reviewed by Dominik Czernia, PhD candidate and Jack Bowater
Last updated: Feb 15, 2022

The HAS-BLED calculator takes into consideration nine crucial factors to help you estimate the one-year bleeding hazard in your patient with atrial fibrillation. The HAS-BLED criteria we use was developed in 2010, and the scoring system, described therein, is considered better at discriminating the major bleeding risk than other scales - according to the guidelines published in the Journal of the American College of Cardiology. In the article below, you will also read more about the HAS-BLED score interpretation and what each point implies.

We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace a professional doctor's assessment. Before administering any drugs, fluids, or treatment to your patient, make sure you know the dose and the method.

How to use the HAS-BLED calculator?

With more care being given to an aging population these days, internal medicine doctors are facing the challenge of atrial fibrillation more and more often. The key here is to balance the risks: the risk of stroke and need of thromboprophylaxis, and the risk of potentially life-threatening bleeding. That's why there is an increasing need for medical scales that help make crucial decisions, like balancing these risks, easier. The risk of stroke can be assessed with the CHA2DS2-VASC scale, while specialists recommend using the HAS-BLED score for determining the major bleeding risk.

In our calculator, all you have to do is select 'Yes' for the bleeding factors that your patient has. They are automatically excluded, so you don't have to answer 'No' separately on every condition that your patient doesn't have. You can find a more detailed description of the factors by hovering the mouse cursor over them or check them all at once in the HAS-BLED criteria section below. The result will be shown immediately, with a quick comment and recommendation.

You should use the HAS-BLED calculator before administering anticoagulation therapy to a patient with atrial fibrillation. Professor Gregory YH Lip, MD emphasises that the aim here is not to exclude patients from pharmacological prophylaxis, but rather flag persons with a high bleeding risk in order to monitor them closely, and consider interventions in potentially reversible bleeding risk factors.

HAS-BLED criteria

The HAS-BLED scale contains nine factors that you need to pay attention to to evaluate the major bleeding risk properly:

  1. Hypertension - often defined as blood pressure over 140/90 mmHg. In the HAS-BLED score you score a point when the SBP (systolic blood pressure) is over 160 mmHg. Remember - the presence of arterial hypertension is not always decisive; uncontrolled blood pressure is the more serious risk factor.
  2. Abnormal renal function - if the patient is on chronic dialysis, has a renal transplant, or a serum-measured creatinine level over 200 µmol/l (2.26 mg/dL) - which is always reflected in the GFR parameter as well.
  3. Abnormal liver function - defined as liver cirrhosis or if biochemical indicators: bilirubin > 2x upper limit normal (UNL) or AST/ASP/AP > 3x UNL.
  4. Stroke history - did the patient have a stroke?
  5. Bleeding - did the patient have prior major bleeding or a bleeding predisposition, like anemia or a reduced hemoglobin level?
  6. Labile INR - the patient is taking oral anticoagulation drugs and has INR measures outside of the therapeutic range at least 40% of the time (TTR - time in therapeutic range). If so, we classify the INR as labile.
  7. Elderly - is the patient 65 years old or older?
  8. Alcohol use - defined as ingesting at least 8 standard drinks weekly.
  9. Drugs - score a point if the patient is taking drugs that predispose them to bleeding, such as antiplatelet agents (acetylsalicylic acid, clopidogrel) or non-steroid anti-inflammatory drugs (e.g., ibuprofen, diclofenac).

HAS-BLED score interpretation

The HAS-BLED score is just one of the clinical tools used to assess a patient with atrial fibrillation. The primary purpose of the scale is to flag any patients with a high major bleeding risk before starting anticoagulation therapy.

The scale should be interpreted individually, and the assessment should consider the whole clinical picture. However, you might find this short table with basic recommendations useful:

0 pointslow risk groupyou should consider anticoagulation
1 - 2 points moderate risk groupyou can consider anticoagulation
⩾ 3 points high risk groupyou should consider alternatives to anticoagulation
- review patient regularly and closely
- monitor INR (International Normalized Ratio) frequently
- consider actions to correct potentially reversible factors

The potentially reversible factors are those of the HAS-BLED scale factors which, as the name says, can be reversed or improved, at least theoretically. They are points of action that should be always taken into consideration while assessing the patient - they contribute not only to bleeding risk, but also to a bunch of other diseases.

List of potentially reversible factors of the HAS-BLED score:

  • hypertension
  • predisposition to bleeding (treating an underlying condition like anemia)
  • labile INR
  • alcohol use
  • concomitant use of other drugs

Definition of major bleeding

HAS-BLED score is used to assess the 1-year major bleeding risk in patients with atrial fibrillation before administering anticoagulation drugs therapy. Major bleeding is defined as:

  • fatal bleeding.
  • clinically overt bleeding.
  • bleeding that causes the hemoglobin level to drop at least 20 g/L (1.24 mmol/L).
  • bleeding that requires transfusion of at least two blood units.
  • bleeding involving a critical anatomic site other than the brain parenchyma.
Aleksandra Zając, MD
If the condition is present in your patient, select "Yes".
Abnormal renal fuction
Abnormal liver function
Stroke history
Labile INR
Age ⩾ 65 years
Alcohol use ⩾ 8 drinks per week
Drugs predisponing to bleeding
The patient is in the low risk group.

The bleeding risk is 0.9%[1]. The number of events (bleeds) per 100 patient-years is 1.1[2].
Patient-year - it's a way of expressing statistic data. It equals the number of patients multiplied by years of observation. If we observed 100 patients for 2 years, the number of patient-years would be 200. If we observe 3 incidents of interest during this time, we could express the number of them as 3 per 200 patient-years or 1.5 per 100 patient-years, or 0.015 per one patient-year.
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