title: Clinical classification schemes for predicting hemorrhage: results from the National Registry of Atrial Fibrillation (NRAF).
abstract: BACKGROUND
  Although warfarin and other anticoagulants can prevent ischemic events, they can cause hemorrhage. Quantifying the rate of hemorrhage is crucial for determining the risks and net benefits of prescribing antithrombotic therapy. Our objective was to find a bleeding classification scheme that could quantify the risk of hemorrhage in elderly patients with atrial fibrillation.
  
  
  METHODS
  We combined bleeding risk factors from existing classification schemes into a new scheme, HEMORR2HAGES, and validated all bleeding classification schemes. We scored HEMORR2HAGES by adding 2 points for a prior bleed and 1 point for each of the other risk factors: hepatic or renal disease, ethanol abuse, malignancy, older (age > 75 years), reduced platelet count or function, hypertension (uncontrolled), anemia, genetic factors, excessive fall risk, and stroke. We used data from quality improvement organizations representing 7 states to assemble a registry of 3791 Medicare beneficiaries with atrial fibrillation.
  
  
  RESULTS
  There were 162 hospital admissions with an International Classification of Diseases, Ninth Revision, Clinical Modification code for hemorrhage. With each additional point, the rate of bleeding per 100 patient-years of warfarin increased: 1.9 for 0, 2.5 for 1, 5.3 for 2, 8.4 for 3, 10.4 for 4, and 12.3 for > or =5 points. In patients prescribed warfarin, HEMORR2HAGES had greater predictive accuracy (c statistic 0.67) than other bleed prediction schemes (P < .001).
  
  
  CONCLUSIONS
  Adaptations of existing classification schemes, especially a new bleeding risk scheme, HEMORR2HAGES, can quantify the risk of hemorrhage and aid in the management of antithrombotic therapy.
authors.affiliation: Division of General Medical Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA. bgage@im.wustl.edu
authors.forename: Brian F
authors.initials: BF
authors.lastname: Gage
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan
authors.forename: Paul E
authors.initials: PE
authors.lastname: Milligan
authors.forename: Amy D
authors.initials: AD
authors.lastname: Waterman
authors.forename: Robert
authors.initials: R
authors.lastname: Culverhouse
authors.forename: Michael W
authors.initials: MW
authors.lastname: Rich
authors.forename: Martha J
authors.initials: MJ
authors.lastname: Radford
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000009:adverse effects* / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000150:complications / Q000188:drug therapy*; D002543:Cerebral Hemorrhage / Q000453:epidemiology; D005260:Female; D006471:Gastrointestinal Hemorrhage / Q000453:epidemiology; D006470:Hemorrhage / Q000139:chemically induced / Q000145:classification / Q000453:epidemiology*; D006801:Humans; D008297:Male; D012042:Registries; D012307:Risk Factors
chemical_list: D000925:Anticoagulants