title: The ORBIT bleeding score: a simple bedside score to assess bleeding risk in atrial fibrillation.
abstract: BACKGROUND
  Therapeutic decisions in atrial fibrillation (AF) are often influenced by assessment of bleeding risk. However, existing bleeding risk scores have limitations.
  
  
  OBJECTIVE
  We sought to develop and validate a novel bleeding risk score using routinely available clinical information to predict major bleeding in a large, community-based AF population.
  
  
  METHODS
  We analysed data from Outcomes Registry for Better Informed Treatment of Atrial Fibrillation (ORBIT-AF), a prospective registry that enrolled incident and prevalent AF patients at 176 US sites. Using Cox proportional hazards regression, we identified factors independently associated with major bleeding among patients taking oral anticoagulation (OAC) over a median follow-up of 2 years (interquartile range = 1.6-2.5). We also created a numerical bedside risk score that included the five most predictive risk factors weighted according to their strength of association with major bleeding. The predictive performance of the full model, the simple five-item score, and two existing risk scores (hypertension, abnormal renal/liver function, stroke, bleeding history or predisposition, labile INR, elderly, drugs/alcohol concomitantly, HAS-BLED, and anticoagulation and risk factors in atrial fibrillation, ATRIA) were then assessed in both the ORBIT-AF cohort and a separate clinical trial population, Rivaroxaban Once-daily oral direct factor Xa inhibition compared with vitamin K antagonism for prevention of stroke and embolism trial in atrial fibrillation (ROCKET-AF).
  
  
  RESULTS
  Among 7411 ORBIT-AF patients taking OAC, the rate of major bleeding was 4.0/100 person-years. The full continuous model (12 variables) and five-factor ORBIT risk score (older age [75+ years], reduced haemoglobin/haematocrit/history of anaemia, bleeding history, insufficient kidney function, and treatment with antiplatelet) both had good ability to identify those who bled vs. not (C-index 0.69 and 0.67, respectively). These scores both had similar discrimination, but markedly better calibration when compared with the HAS-BLED and ATRIA scores in an external validation population from the ROCKET-AF trial.
  
  
  CONCLUSIONS
  The 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. The ORBIT risk score can provide a simple, easily remembered tool to support clinical decision making.
authors.affiliation: Duke Clinical Research Institute, 2400 Pratt Street, Durham, NC 27705, USA emily.obrien@duke.edu.
authors.forename: Emily C
authors.initials: EC
authors.lastname: O'Brien
authors.affiliation: Duke Clinical Research Institute, 2400 Pratt Street, Durham, NC 27705, USA.
authors.forename: DaJuanicia N
authors.initials: DN
authors.lastname: Simon
authors.affiliation: Duke Clinical Research Institute, 2400 Pratt Street, Durham, NC 27705, USA.
authors.forename: Laine E
authors.initials: LE
authors.lastname: Thomas
authors.affiliation: Boston University School of Medicine, Boston, MA, USA.
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Hylek
authors.affiliation: Mayo Clinic, Rochester, MN, USA.
authors.forename: Bernard J
authors.initials: BJ
authors.lastname: Gersh
authors.affiliation: Hofstra North Shore/LIJ School of Medicine, Hempstead, NY, USA.
authors.forename: Jack E
authors.initials: JE
authors.lastname: Ansell
authors.affiliation: Jefferson Medical College, Philadelphia, PA, USA.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Kowey
authors.affiliation: Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Mahaffey
authors.affiliation: Janssen Scientific Affairs, Raritan, NJ, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Chang
authors.affiliation: UCLA Division of Cardiology, Los Angeles, CA, USA.
authors.forename: Gregg C
authors.initials: GC
authors.lastname: Fonarow
authors.affiliation: Duke Clinical Research Institute, 2400 Pratt Street, Durham, NC 27705, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Pencina
authors.affiliation: Duke Clinical Research Institute, 2400 Pratt Street, Durham, NC 27705, USA.
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Piccini
authors.affiliation: Duke Clinical Research Institute, 2400 Pratt Street, Durham, NC 27705, USA.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Peterson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000009:adverse effects*; D001281:Atrial Fibrillation / Q000188:drug therapy*; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced* / Q000517:prevention & control; D006801:Humans; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D011446:Prospective Studies; D012042:Registries; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D020521:Stroke / Q000517:prevention & control
chemical_list: D000925:Anticoagulants
keywords: Anticoagulants; Atrial fibrillation; Major bleeding; Risk prediction