Deep vein thrombosis: d-dimers may help exclude DVT.

Clinical bottom line (level 4)

  1. In patients with suspected deep venous thrombosis, d-dimer tests could help rule it out, but with wide confidence intervals, further testing is required.
Dale et al: Thrombosis and Haemostasis 1994; 71 (3): 270-274
Expires May 2003

The study

Setting: university hospital, Norway

92 patients (aged ?, 52% female) clinically suspected deep vein thrombosis referred for venogram

Non-independent blinded reference standard, applied in all patients from a consecutive appropriate spectrum.
Reference standard:
  • venogram- confirmed by two independent reviewers
Diagnostic test: Nycocard d-dimer (immunofiltration test- cut-off set at >500 ng/dl); ELISA d-dimer- cut-off 250 ng/ml; latex agglutination d-dimer test

The evidence

pre-test probability of deep vein thrombosis: 44%, (95% CI: 33% to 54%)

diagnostic test deep vein thrombosis no deep vein thrombosis LR+
(95% CI)		 post-test probability LR-
(95% CI)		 post-test probability
immunofiltration (>500 ng/dl) 38 39 1.27
(1.07 to 1.50) 		49% 0.20
(0.05 to 0.84) 		13%
ELISA (>250 ng/dl) 39 32 1.58
(1.27 to 1.98) 		55% 0.065
(0.091 to 0.46) 		5%
latex agglutination 29 13 2.90
(1.74 to 4.82) 		69% 0.37
(0.22 to 0.62) 		22%
total 40 52

  • Laboratory variation was great in immunofiltration - specificities varied from 25% to 48% on the same samples.

Comments

  1. Cut-off values for test not predetermined - perhaps this was decided on the basis of test results
  2. ELISA tests take several hours to perform.
  3. Whole blood agglutination tests are now available, which can be used at the bedside and are more rapid.
  4. Test characteristics vary greatly between tests, so the study may not be that widely applicable.

Citation

  1. Dale S, Gogstad GO, Brosstad F, et al: Comparison of three d-dimer assays for the diagnosis of DVT: ELISA, latex and an immunofiltration assay (Nycocard D-Dimer). Thrombosis and Haemostasis 1994; 71 (3): 270-274
Contributor: Chris Ball and Clare Wotton, May 2000
Reviewer: Alex Gallus

Clinical Question.
Patient clinically suspected deep vein thrombosis referred for venogram
Intervention or Exposure d-dimer tests
Comparison venogram
Outcome diagnosis