The HAS-BLED score is a clinical tool used to assess the risk of major bleeding in patients with atrial fibrillation (AF) who are undergoing anticoagulation therapy. It was developed to aid healthcare professionals in balancing the benefits of anticoagulation, which reduces the risk of stroke, against the potential harm from bleeding complications. For an easy calculation, you can use our HAS-BLED Calculator. The acronym HAS-BLED stands for Hypertension, Abnormal renal/liver function, Stroke, Bleeding history or predisposition, Labile International Normalized Ratios (INRs), Elderly (age over 65), and Drugs or alcohol concomitantly.

The HAS-BLED score assigns points to each risk factor, with a total possible score ranging from 0 to 9. A higher score indicates a greater risk of bleeding. Here’s a breakdown of the components:

Hypertension: Uncontrolled blood pressure, specifically systolic blood pressure above 160 mmHg, is a known risk factor for bleeding. Patients with hypertension are assigned one point.

Abnormal renal/liver function: One point is assigned for abnormal renal function, such as chronic dialysis, renal transplantation, or serum creatinine ≥200 µmol/L. Another point is given for abnormal liver function, such as chronic hepatic disease or significant hepatic derangement. If both are present, the patient receives two points.

Stroke history: Patients with a previous history of stroke are at a higher risk of bleeding and are assigned one point.

Bleeding history or predisposition: A history of major bleeding or conditions predisposing to bleeding, such as bleeding diathesis or anemia, earns one point.

Labile INRs: Patients with unstable or high INRs (International Normalized Ratios) are assigned one point. This criterion applies mainly to those on warfarin therapy, where maintaining a therapeutic INR range is critical.

Elderly: Age over 65 is a significant risk factor for bleeding, and elderly patients are assigned one point.

Drugs or alcohol concomitantly: Patients who use drugs that predispose to bleeding, such as antiplatelet agents or non-steroidal anti-inflammatory drugs (NSAIDs), or those with excess alcohol intake (defined as ≥8 units/week) are given one point.

The total HAS-BLED score is calculated by summing the points for each of these risk factors. The interpretation of the score is straightforward: a score of 0-1 indicates a low risk of bleeding, 2-3 suggests a moderate risk, and a score of 4 or higher indicates a high risk of bleeding. This score assists clinicians in making informed decisions about initiating or continuing anticoagulation therapy.

Despite its utility, the HAS-BLED score is not without limitations. It does not account for some other important factors influencing bleeding risk, such as the presence of cancer or the use of certain newer anticoagulants. Additionally, it is primarily based on data from patients with AF and may not be as applicable to those with other indications for anticoagulation.

The HAS-BLED score should not be used in isolation but rather as part of a comprehensive clinical assessment. It is a tool to aid in decision-making and should be considered alongside other factors, including patient preferences, the risk of thromboembolism, and overall clinical judgment.