Venous thromboembolism: some d-dimer tests may rule out PE and DVT.

Clinical bottom line (level 1a)

  1. Diagnostic characteristics vary greatly among d-dimer testing kits.
  2. Most methods cannot usefully rule in or rule out pulmonary embolism or deep vein thrombosis.
  3. A negative SimpliRED test makes venous thromboembolism less likely (LR-0.091) .
Becker et al: Archives of Internal Medicine 1996; 156: 939-946
Expires September 2003

The study

Systematic review of all of
  • Patients: suspected pulmonary embolism or deep vein thrombosis
  • Intervention: d-dimer tests compared with venogram for DVT and ventilation-perfusion scan plus various clinical and laboratory criteria for PE
  • Outcome: diagnosis of deep vein thrombosis or pulmonary embolism


    • Articles found in English using MEDLINE, Current Contents, 1985 to 1995 (search terms: not detailed ) and reviewing references from articles found

    Selection criteria: as above
    Appraisal criteria: selected by three independent reviewers using set criteria
    Articles excluded if:

    Thirteen of twenty-nine identified studies studies were included.
    Studies showed a wide variation in test characteristics, although heterogeneity was not formally examined .

    The evidence


    diagnostic test venous thromboembolism no VTE LR+
    (95% CI)    		 LR-
    (95% CI)
    latex d-dimer 292 323 1.8
    (1.6 to 1.9)     		0.28
    (0.21 to 0.36)
    whole blood agglutination (SimpliRED) 320 224 2.8
    (2.5 to 3.1)     		0.091
    (0.06 to 0.14)
    total 340 660

    Comments

    1. d-dimer- a specific degradation product released by endogenous fibrinolysis (also increased in surgical patients).
    2. Few tests have been repeatedly validated.
    3. d-dimer tests:
      • ELISA- accurate but too slow to be clinically useful
      • agglutination tests- less accurate
    4. Great variation between individual d-dimer testing kits in terms of sensitivity and specificity. Also many patient cohorts were not selected in unbiased manner (eg. already booked for ultrasound scan or venogram). Thus it is difficult to combine the studies and to generalise about the applicability of the test from setting to setting.
    5. There are gold standard problems since d-dimer detects clot formation anywhere- thus there is a need to check for both DVT and PE to be confident that there is correlation between d-dimer levels and clot. This occurred in a few studies.
    6. No test is good enough alone to rule out pulmonary embolism to a safe level.

    Citation

    1. Becker DM, Philbrick JT, Bachhuber TL, et al: d-dimer testing and acute venous thromboembolism: a shortcut to accurate diagnosis?. Archives of Internal Medicine 1996; 156: 939-946
    Contributor: Chris Ball and Clare Wotton, Unknown Month 2000
    Reviewer: Alex Gallus

    Clinical Question.
    Patient suspected venous thromboembolism
    Intervention or Exposure d-dimer tests
    Outcome diagnosis of PE or DVT