title: Warfarin use leads to larger intracerebral hematomas.
abstract: BACKGROUND
  Among patients with intracerebral hemorrhage (ICH), warfarin use before onset leads to greater mortality. In a retrospective study, we sought to determine whether warfarin use is associated with larger initial hematoma volume, one determinant of mortality after ICH.
  
  
  METHODS
  We identified all patients hospitalized with ICH in the Greater Cincinnati region from January through December 2005. ICH volumes were measured on the first available brain scan by using the abc/2 method. Univariable analyses and a multivariable generalized linear model were used to determine whether international normalized ratio (INR) influenced initial ICH volume after adjusting for other factors, including age, race, sex, antiplatelet use, hemorrhage location, and time from stroke onset to scan.
  
  
  RESULTS
  There were 258 patients with ICH, including 51 patients taking warfarin. In univariable comparison, when INR was stratified, there was a trend toward a difference in hematoma volume by INR category (INR <1.2, 13.4 mL; INR 1.2-2.0, 9.3 mL; INR 2.1-3.0, 14.0 mL; INR >3.0, 33.2 mL; p = 0.10). In the model, compared with patients with INR <1.2, there was no difference in hematoma size for patients with INR 1.2-2.0 (p = 0.25) or INR 2.1-3.0 (p = 0.36), but patients with INR >3.0 had greater hematoma volume (p = 0.02). Other predictors of larger hematoma size were ICH location (lobar compared with deep cerebral, p = 0.02) and shorter time from stroke onset to scan (p < 0.001).
  
  
  CONCLUSIONS
  Warfarin use was associated with larger initial intracerebral hemorrhage (ICH) volume, but this effect was only observed for INR values >3.0. Larger ICH volume among warfarin users likely accounts for part of the excess mortality in this group.
authors.affiliation: Department of Neurology, University of Cincinnati Academic Health Center, Cincinnati, OH 45267-0525, USA. matthew.flaherty@uc.edu
authors.forename: M L
authors.initials: ML
authors.lastname: Flaherty
authors.forename: H
authors.initials: H
authors.lastname: Tao
authors.forename: M
authors.initials: M
authors.lastname: Haverbusch
authors.forename: P
authors.initials: P
authors.lastname: Sekar
authors.forename: D
authors.initials: D
authors.lastname: Kleindorfer
authors.forename: B
authors.initials: B
authors.lastname: Kissela
authors.forename: P
authors.initials: P
authors.lastname: Khatri
authors.forename: B
authors.initials: B
authors.lastname: Stettler
authors.forename: O
authors.initials: O
authors.lastname: Adeoye
authors.forename: C J
authors.initials: CJ
authors.lastname: Moomaw
authors.forename: J P
authors.initials: JP
authors.lastname: Broderick
authors.forename: D
authors.initials: D
authors.lastname: Woo
mesh_terms: D017668:Age of Onset; D000368:Aged; D000925:Anticoagulants / Q000009:adverse effects*; D001921:Brain / Q000098:blood supply / Q000000981:diagnostic imaging / Q000473:pathology; D015984:Causality; D002536:Cerebral Arteries / Q000000981:diagnostic imaging / Q000187:drug effects / Q000473:pathology; D002543:Cerebral Hemorrhage / Q000139:chemically induced* / Q000175:diagnosis* / Q000503:physiopathology; D018450:Disease Progression; D006801:Humans; D019934:International Normalized Ratio; D008279:Magnetic Resonance Imaging; D015999:Multivariate Analysis; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed; D014859:Warfarin / Q000009:adverse effects*
chemical_list: D000925:Anticoagulants; D010975:Platelet Aggregation Inhibitors; D014859:Warfarin