ORBIT Bleeding Score Calculator

ORBIT Bleeding Score: Explanation and Clinical Context The ORBIT Bleeding Score is a validated clinical tool designed to predict the annual risk of major bleeding in patients with atrial fibrillation receiving oral anticoagulant therapy. Developed from the large-scale ORBIT-AF (Outcomes Registry for Better Informed Treatment of Atrial Fibrillation) study, it incorporates five easily available clinical variables: older age (≥75 years), reduced hemoglobin or anemia, previous bleeding history, impaired renal function (eGFR <60 mL/min/1.73m²), and concurrent antiplatelet use. Each factor contributes to the total score (range 0–7), allowing clinicians to stratify bleeding risk into three main categories: low (0–2 points), intermediate (3 points), and high (4–7 points).

The predicted annual bleeding rates were approximately 2.4%, 4.7%, and 8.1%, respectively. The model showed good calibration and discrimination (C-statistic 0.67) and performed favorably compared to HAS-BLED and ATRIA scores, especially among patients treated with direct oral anticoagulants. Clinically, the ORBIT score is useful for tailoring anticoagulant therapy, monitoring patients at high bleeding risk, and guiding shared decision-making.

It complements other risk models and is included in major atrial fibrillation guidelines (ACC/AHA/HRS 2023) as an accepted tool for bleeding risk assessment.