title: Efficacy of warfarin reversal in orthopedic trauma surgery patients.
abstract: OBJECTIVE
  We determine the efficacy of active reversal of warfarin anticoagulation with intravenous vitamin K compared to withholding warfarin in patients requiring urgent orthopedic trauma surgery.
  
  
  METHODS
  This was a prospective cohort with immediate prehypothesis consecutive retrospective comparative case series conducted at a level 1 university hospital trauma unit.
  
  
  METHODS
  Forty-eight consecutive patients between 1998 and 2004 in a study composed of a prospective cohort were compared with a retrospective consecutive case series of warfarinized orthopedic trauma patients requiring urgent surgery. The prospective arm directly followed the historic case series from which the hypothesis was generated.
  
  
  METHODS
  Vitamin K administration.
  
  
  METHODS
  Primary outcome was time to surgery. Secondary outcomes were problems with active reversal, length of time for warfarin stabilization after surgery, and complications.
  
  
  RESULTS
  The mean time to surgery in warfarinized patients not given vitamin K was 111.9 hours; in the intervention group, it was 67.4 hours, giving a mean difference of 44.5 hours (P = 0.01). Vitamin K reduced the international normalized ratio (INR) to less than 2.0 in 74% of patients within 24 hours. There were no complications of vitamin K administration. A dose of vitamin K costs approximately 1/1000 of a hospital bed day cost. A loading dose of warfarin on the second postoperative day took approximately 1 day longer to reach an INR of greater than 2.0 in the intervention patients than in those who had not been given vitamin K.
  
  
  CONCLUSIONS
  Warfarin reversal with vitamin K was successful and facilitated earlier surgery in all patients; the first dose was effective in approximately three quarters of patients. It is cost-effective, with no side effects caused in this study.
authors.affiliation: Kadoorie Centre for Critical Care Research, John Radcliffe Hospital, Oxford, United Kingdom.
authors.forename: Pritam
authors.initials: P
authors.lastname: Tharmarajah
authors.forename: Jane
authors.initials: J
authors.lastname: Pusey
authors.forename: David
authors.initials: D
authors.lastname: Keeling
authors.forename: Keith
authors.initials: K
authors.lastname: Willett
mesh_terms: D000284:Administration, Oral; D000925:Anticoagulants / Q000008:administration & dosage*; D001777:Blood Coagulation / Q000187:drug effects*; D001778:Blood Coagulation Disorders / Q000517:prevention & control; D015331:Cohort Studies; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D019637:Orthopedic Procedures; D011300:Preoperative Care / Q000379:methods*; D013927:Thrombosis / Q000517:prevention & control; D016896:Treatment Outcome; D014812:Vitamin K / Q000008:administration & dosage*; D014859:Warfarin / Q000008:administration & dosage*; D014947:Wounds and Injuries / Q000601:surgery*
chemical_list: D000925:Anticoagulants; D014812:Vitamin K; D014859:Warfarin