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ORBIT bleeding risk score

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

NICE have suggested that the ORBIT bleeding risk score should be used (in comparison to other bleeding risk scoring systems such as HAS-BLED) in assessing the risk of bleeding when a patient commences, or is under review, regarding anticoagulation therapy in atrial fibrillation (1).

NICE state that "because evidence shows that it has a higher accuracy in predicting absolute bleeding risk than other bleeding risk tools. Accurate knowledge of bleeding risk supports shared decision making and has practical benefits, for example, increasing patient confidence and willingness to accept treatment when risk is low and prompting discussion of risk reduction when risk is high. Although ORBIT is the best tool for this purpose, other bleeding risk tools may need to be used until it is embedded in clinical pathways and electronic systems"

O'Brien et al devised the ORBIT bleeding risk scoring system:

  • using data from the national Outcomes Registry for Better Informed Treatment of Atrial Fibrillation (ORBIT-AF) registry, O'Brien et al constructed a full continuous predictive model as well as a simple risk score for major bleeding among patients who were taking OAC therapy

  • developed a five-factor numerical bleeding risk score from the five strongest predictors termed ORBIT:

Risk Factor For Bleeding

Points Attributed

(older (75 years or older)

1 point

reduced haemoglobin (<13 mg/dL in men and <12 mg/dL in women), haematocrit (<40% in men and <36% in women) or history of anaemia

2 points

bleeding history

2 points

insufficient kidney function (eGFR < 60 mg/dL/1.73 m2)

1 point

treatment with an antiplatelet agent

1 point

  • Interpretation:


Risk group

Bleeds per 100 patient-years










  • reduced haemoglobin/anaemia was most strongly associated with major bleeding, followed by bleeding history, treatment with antiplatelets, insufficient kidney function, and older age

  • five-element ORBIT bleeding risk score had better ability to predict major bleeding in AF patients when compared with HAS-BLED and ATRIA risk scores (2)
    • the ORBIT risk score can provide a simple, easily remembered tool to support clinical decision making

Click here for online ORBIT risk calculator


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