title: Aspirin versus warfarin in atrial fibrillation: decision analysis may help patients' choice.
abstract: BACKGROUND
  the primary prevention of ischaemic stroke in chronic non-valvular atrial fibrillation (AF) typically involves consideration of aspirin or warfarin. CHA(2)DS(2)-VASc estimates annual stroke rates for untreated AF patients, which are reduced by 60% with warfarin and by 20% with aspirin. HAS-BLED estimates annual rates of major bleeding on warfarin. The latter risk with aspirin is 0.5-1.2% per year.
  
  
  OBJECTIVE
  given a 'warfarin, aspirin or no therapy' choice, AF patients will prefer the option that maximises the annual probability of not having a stroke and not having a major bleed.
  
  
  METHODS
  decision tree applied to the 60 possible combinations of CHA(2)DS(2)-VASc and HAS-BLED scores.
  
  
  RESULTS
  according to the pre-specified hypothesis, when CHA(2)DS(2)-VASc is <2, the balance of risk and benefit would advise no treatment; when CHA(2)DS(2)-VASc is 2 or 3, warfarin would be best when HAS-BLED <2, otherwise no treatment would be advised; for CHA(2)DS(2)-VASc =4, warfarin would be best when HAS-BLED <3, otherwise no treatment would be advised and for CHA(2)DS(2)-VASc ≥5, warfarin would be the preferred option if HAS-BLED <4, otherwise aspirin would be advised.
  
  
  CONCLUSIONS
  this theoretical exercise illustrates the potential benefit of decision analysis in an area where high complexity and uncertainty still remain.
authors.affiliation: St Vincent's University Hospital, Department of Medicine for the Elderly, Elm Park, Dublin 4, Ireland. romeror@tcd.ie
authors.forename: Roman
authors.initials: R
authors.lastname: Romero-Ortuno
authors.forename: Diarmuid
authors.initials: D
authors.lastname: O'Shea
mesh_terms: D000925:Anticoagulants / Q000009:adverse effects / Q000627:therapeutic use*; D001241:Aspirin / Q000009:adverse effects / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000150:complications / Q000188:drug therapy*; D003661:Decision Support Techniques; D003663:Decision Trees; D006470:Hemorrhage / Q000139:chemically induced; D006801:Humans; D018579:Patient Selection; D011322:Primary Prevention / Q000379:methods*; D018570:Risk Assessment; D012307:Risk Factors; D020521:Stroke / Q000209:etiology / Q000517:prevention & control*; D016896:Treatment Outcome; D014859:Warfarin / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014859:Warfarin; D001241:Aspirin