ORBIT Bleeding Risk Score for Atrial Fibrillation

ORBIT Calculator

Age ≥75 Years

Reduced Hemoglobin/Hematocrit/Anemia

Bleeding History

Renal Insufficiency (GFR <60 mL/min)

Treatment with Antiplatelet Agent

ORBIT Score: 0

Low Risk

Score 0: Low bleeding risk (2.4% bleeds/year). Anticoagulation generally favorable.

Predicts bleeding risk in patients on anticoagulation for afib, similar to HAS-BLED .

Why Use

May be used in conjunction with the CHA₂DS₂-VASc Score to risk stratify patients for clinically significant bleeding to help guide decisions on anticoagulation in patients with atrial fibrillation. May not be statistically superior to HAS-BLED (see Evidence for details), but was more recently derived and validated in the era of DOACs, and may be more useful for that reason.

When to Use

Patients with atrial fibrillation in whom anticoagulation is being considered for stroke prevention.

Formula

Addition of the selected points: Variable Points Hemoglobin <13 g/dL for males and <12 g/dL for females, or hematocrit <40% for males and <36% for females No 0 Yes 2 Age >74 years No 0 Yes 1 Bleeding history* No 0 Yes 2 GFR <60 mL/min/1.73 m 2 No 0 Yes 1 Treatment with antiplatelet agents No 0 Yes 1 *Any history of GI bleeding, intracranial bleeding, or hemorrhagic stroke.

Pearls / Pitfalls

Major bleeding was defined as fatal bleeding, symptomatic bleeding in a critical organ, or bleeding with a hemoglobin drop requiring transfusion of ≥2 units ( ISTH criteria). ORBIT does not take into account choice of anticoagulant. Unlike HAS-BLED , ORBIT does not take into account the time in therapeutic range, as there is no reliable or readily available objective measure for therapeutic range of the direct oral anticoagulants (DOACs). Unlike HAS-BLED, ORBIT was derived in a patient population that included vitamin K antagonists (VKAs, such as warfarin) as well as DOACs.

Critical Actions

Other risk factors not part of the ORBIT Score may influence the decision for anticoagulation. Patient preferences and values should go into the decision regarding anticoagulation as it pertains to risks vs. benefits of being on anticoagulation for stroke prevention in patients with atrial fibrillation.

More Information

Interpretation: ORBIT Score Risk group Bleeds per 100 patient-years 0-2 Low 2.4 3 Medium 4.7 4-7 High 8.1 From O'Brien 2015 .