title: Practical utility of the D-dimer assay for excluding thromboembolism in severely injured trauma patients.
abstract: BACKGROUND
  We have advocated the use of a D-dimer assay to exclude the diagnosis of pulmonary embolism (PE) and deep venous thrombosis (DVT) in surgical and trauma patients suspected of having these diagnoses. Injury is known to increase D-dimer levels independent of thromboembolism. The purpose of this study was to assess the period after injury over which the D-dimer assay remains positive because of injury exclusive of thromboembolism.
  
  
  METHODS
  We prospectively sampled the plasma of severely injured patients for D-dimer using an enzyme-linked immunosorbent assay method at admission; at hours 8, 16, 24, and 48; and at days 3, 4, 5, and 6. Patients were then screened for DVT with a routine duplex Doppler at day 7. Patients were followed for PE, adult respiratory distress syndrome, and disseminated intravascular coagulation.
  
  
  RESULTS
  One hundred fifty-four patients (mean Injury Severity Score of 23) underwent a total of 1,230 D-dimer assays. Twenty-six (17%) had thromboembolism. Nine (6%) patients developed DVT, 2 (1%) developed PE, 13 (8%) developed disseminated intravascular coagulation, and 11 (7%) developed severe adult respiratory distress syndrome. None of the trauma patients with thromboembolism had a (false) negative D-dimer at or after the time of their thromboembolic complication. True-negative D-dimer results as a function of time from injury are: 0 hours, 18%; 8 hours, 16%; 16 hours, 17%; 24 hours, 22%; 48 hours, 37%; day 3, 34%; day 4, 32%; day 5, 30%; and day 6, 30%. The negative predictive value of the assay was 100%. D-dimer levels were significantly higher in those who developed a thromboembolic complication than in those who did not (independent of Injury Severity Score).
  
  
  CONCLUSIONS
  These data serve to validate D-dimer as a means of excluding thromboembolism, specifically in patients with severe injury (100% negative predictive value). Before 48 hours after injury, however, the vast majority of these patients without thromboembolism had positive D-dimer assays. Because of the high false-positive rate early after severe injury, the D-dimer assay may be of little value before postinjury hour 48.
authors.affiliation: Trauma Division, University of California-Davis, 23155 Stockton Blvd., Sacramento, CA 95817, USA. jtowings@ucdavis.edu
authors.forename: J T
authors.initials: JT
authors.lastname: Owings
authors.forename: R C
authors.initials: RC
authors.lastname: Gosselin
authors.forename: J T
authors.initials: JT
authors.lastname: Anderson
authors.forename: F D
authors.initials: FD
authors.lastname: Battistella
authors.forename: M
authors.initials: M
authors.lastname: Bagley
authors.forename: E C
authors.initials: EC
authors.lastname: Larkin
mesh_terms: D000328:Adult; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000378:metabolism*; D006801:Humans; D015601:Injury Severity Score; D008297:Male; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000097:blood / Q000175:diagnosis; D013923:Thromboembolism / Q000097:blood / Q000175:diagnosis*; D013997:Time Factors; D014947:Wounds and Injuries / Q000097:blood* / Q000150:complications
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D