title: Comparing the prothrombin time INR versus the APTT to evaluate the coagulopathy of acute trauma.
abstract: BACKGROUND
  In trauma patients, PT/INR or aPTT cutoffs of > or =1.5x normal are often used as triggers for the transfusion of plasma.
  
  
  METHODS
  To evaluate the ability of the PT/INR or aPTT to predict low coagulation factor levels, these tests were compared to coagulation factor levels in samples with artificially prepared single and multiple factor deficiencies, 9 heparin-contaminated samples, 10 lupus inhibitor-containing samples, 21 samples with elevated factor VIII levels, and 35 samples from acute trauma patients.
  
  
  CONCLUSIONS
  The PT/INR and aPTT showed comparable sensitivity for single or multiple factor deficiencies in artificially deficient plasmas, but the PT/INR was more sensitive than the aPTT to low coagulation factor levels in actual trauma patients (sensitivity 84% versus 50%). The aPTT can show false positives with lupus anticoagulants and heparin contamination and false negatives in samples with elevated factor VIII. Thus, in the acute trauma setting, the PT/INR cutoff is a more reliable indicator of reduced coagulation factor levels.
authors.affiliation: Department of Laboratory Medicine, Box 357110, University of Washington, Seattle, WA 98195-7110, USA.
authors.forename: Shan
authors.initials: S
authors.lastname: Yuan
authors.forename: Chris
authors.initials: C
authors.lastname: Ferrell
authors.forename: Wayne L
authors.initials: WL
authors.lastname: Chandler
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001779:Blood Coagulation Factors / Q000378:metabolism*; D002648:Child; D005260:Female; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D008875:Middle Aged; D010314:Partial Thromboplastin Time; D011237:Predictive Value of Tests; D011517:Prothrombin Time; D012680:Sensitivity and Specificity; D014947:Wounds and Injuries / Q000097:blood*
chemical_list: D001779:Blood Coagulation Factors