title: Immediate and delayed traumatic intracranial hemorrhage in patients with head trauma and preinjury warfarin or clopidogrel use.
abstract: OBJECTIVE
  Patients receiving warfarin or clopidogrel are considered at increased risk for traumatic intracranial hemorrhage after blunt head trauma. The prevalence of immediate traumatic intracranial hemorrhage and the cumulative incidence of delayed traumatic intracranial hemorrhage in these patients, however, are unknown. The objective of this study is to address these gaps in knowledge.
  
  
  METHODS
  A prospective, observational study at 2 trauma centers and 4 community hospitals enrolled emergency department (ED) patients with blunt head trauma and preinjury warfarin or clopidogrel use from April 2009 through January 2011. Patients were followed for 2 weeks. The prevalence of immediate traumatic intracranial hemorrhage and the cumulative incidence of delayed traumatic intracranial hemorrhage were calculated from patients who received initial cranial computed tomography (CT) in the ED. Delayed traumatic intracranial hemorrhage was defined as traumatic intracranial hemorrhage within 2 weeks after an initially normal CT scan result and in the absence of repeated head trauma.
  
  
  RESULTS
  A total of 1,064 patients were enrolled (768 warfarin patients [72.2%] and 296 clopidogrel patients [27.8%]). There were 364 patients (34.2%) from Level I or II trauma centers and 700 patients (65.8%) from community hospitals. One thousand patients received a cranial CT scan in the ED. Both warfarin and clopidogrel groups had similar demographic and clinical characteristics, although concomitant aspirin use was more prevalent among patients receiving clopidogrel. The prevalence of immediate traumatic intracranial hemorrhage was higher in patients receiving clopidogrel (33/276, 12.0%; 95% confidence interval [CI] 8.4% to 16.4%) than patients receiving warfarin (37/724, 5.1%; 95% CI 3.6% to 7.0%), relative risk 2.31 (95% CI 1.48 to 3.63). Delayed traumatic intracranial hemorrhage was identified in 4 of 687 (0.6%; 95% CI 0.2% to 1.5%) patients receiving warfarin and 0 of 243 (0%; 95% CI 0% to 1.5%) patients receiving clopidogrel.
  
  
  CONCLUSIONS
  Although there may be unmeasured confounders that limit intergroup comparison, patients receiving clopidogrel have a significantly higher prevalence of immediate traumatic intracranial hemorrhage compared with patients receiving warfarin. Delayed traumatic intracranial hemorrhage is rare and occurred only in patients receiving warfarin. Discharging patients receiving anticoagulant or antiplatelet medications from the ED after a normal cranial CT scan result is reasonable, but appropriate instructions are required because delayed traumatic intracranial hemorrhage may occur.
authors.affiliation: Department of Emergency Medicine, UC Davis School of Medicine, Sacramento, CA, USA. daniel.nishijima@ucdmc.ucdavis.edu
authors.forename: Daniel K
authors.initials: DK
authors.lastname: Nishijima
authors.forename: Steven R
authors.initials: SR
authors.lastname: Offerman
authors.forename: Dustin W
authors.initials: DW
authors.lastname: Ballard
authors.forename: David R
authors.initials: DR
authors.lastname: Vinson
authors.forename: Uli K
authors.initials: UK
authors.lastname: Chettipally
authors.forename: Adina S
authors.initials: AS
authors.lastname: Rauchwerger
authors.forename: Mary E
authors.initials: ME
authors.lastname: Reed
authors.forename: James F
authors.initials: JF
authors.lastname: Holmes
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000009:adverse effects*; D000077144:Clopidogrel; D006259:Craniocerebral Trauma / Q000150:complications* / Q000000981:diagnostic imaging; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D020300:Intracranial Hemorrhages / Q000000981:diagnostic imaging / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D010975:Platelet Aggregation Inhibitors / Q000009:adverse effects*; D011446:Prospective Studies; D012306:Risk; D013988:Ticlopidine / Q000009:adverse effects / Q000031:analogs & derivatives*; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D014859:Warfarin / Q000009:adverse effects*
chemical_list: D000925:Anticoagulants; D010975:Platelet Aggregation Inhibitors; D014859:Warfarin; D000077144:Clopidogrel; D013988:Ticlopidine