title: The predictive ability of the CHADS2 and CHA2DS2-VASc scores for bleeding risk in atrial fibrillation: the MAQI(2) experience.
abstract: BACKGROUND
  Guidelines recommend the assessment of stroke and bleeding risk before initiating warfarin anticoagulation in patients with atrial fibrillation. Many of the elements used to predict stroke also overlap with bleeding risk in atrial fibrillation patients and it is tempting to use stroke risk scores to efficiently estimate bleeding risk. Comparison of stroke risk scores to bleeding risk scores to predict bleeding has not been thoroughly assessed.
  
  
  METHODS
  2600 patients followed at seven anticoagulation clinics were followed from October 2009-May 2013. Five risk models (CHADS2, CHA2DS2-VASc, HEMORR2HAGES, HAS-BLED and ATRIA) were retrospectively applied to each patient. The primary outcome was the first major bleeding event. Area under the ROC curves were compared with C statistic and net reclassification improvement (NRI) analysis was performed.
  
  
  RESULTS
  110 patients experienced a major bleeding event in 2581.6 patient-years (4.5%/year). Mean follow up was 1.0±0.8years. All of the formal bleeding risk scores had a modest predictive value for first major bleeding events (C statistic 0.66-0.69), performing better than CHADS2 and CHA2DS2-VASc scores (C statistic difference 0.10 - 0.16). NRI analysis demonstrated a 52-69% and 47-64% improvement of the formal bleeding risk scores over the CHADS2 score and CHA2DS2-VASc score, respectively.
  
  
  CONCLUSIONS
  The CHADS2 and CHA2DS2-VASc scores did not perform as well as formal bleeding risk scores for prediction of major bleeding in non-valvular atrial fibrillation patients treated with warfarin. All three bleeding risk scores (HAS-BLED, ATRIA and HEMORR2HAGES) performed moderately well.
authors.affiliation: Cardiovascular Center, University of Michigan Health System, Ann Arbor, MI. Electronic address: gbarnes@umich.edu.
authors.forename: Geoffrey D
authors.initials: GD
authors.lastname: Barnes
authors.affiliation: Cardiovascular Center, University of Michigan Health System, Ann Arbor, MI.
authors.forename: Xiaokui
authors.initials: X
authors.lastname: Gu
authors.affiliation: Cardiovascular Center, University of Michigan Health System, Ann Arbor, MI.
authors.forename: Brian
authors.initials: B
authors.lastname: Haymart
authors.affiliation: Cardiovascular Center, University of Michigan Health System, Ann Arbor, MI.
authors.forename: Eva
authors.initials: E
authors.lastname: Kline-Rogers
authors.affiliation: William Beaumont Hospital, Troy, MI.
authors.forename: Steve
authors.initials: S
authors.lastname: Almany
authors.affiliation: Huron Valley Sinai Hospital, Commerce, MI.
authors.forename: Jay
authors.initials: J
authors.lastname: Kozlowski
authors.affiliation: West Michigan Heart, Grand Rapids, MI.
authors.forename: Dennis
authors.initials: D
authors.lastname: Besley
authors.affiliation: Henry Ford Hospital, Detroit, MI.
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Krol
authors.affiliation: Cardiovascular Center, University of Michigan Health System, Ann Arbor, MI.
authors.forename: James B
authors.initials: JB
authors.lastname: Froehlich
authors.affiliation: Hurley Medical Center, Flint, MI.
authors.forename: Scott
authors.initials: S
authors.lastname: Kaatz
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000009:adverse effects / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000150:complications*; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced* / Q000209:etiology; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D020521:Stroke / Q000209:etiology / Q000517:prevention & control*; D014859:Warfarin / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014859:Warfarin
keywords: Anticoagulants; Atrial Fibrillation; Risk Factors; Stroke; Warfarin