Deep vein thrombosis: IPG plus d-dimer testing was better than either alone at diagnosing or excluding.

Clinical bottom line (level 1b)

  1. In patients with suspected first episode deep vein thrombosis, d-dimer and impedance plethysmography together could diagnose and rule it out.
Ginsberg et al: Archives of Internal Medicine 1997; 157: 1077-1081
Expires May 2003

The study

Setting: four university hospitals, Canada

398 patients (aged mean 65 years, 65% female) suspected first episode deep vein thrombosis

Excluded if
  • limited life expectancy
  • contrast media allergy
  • on long term warfarin
  • had received heparin >48 hours
  • absence of symptoms for > 5 days
  • pregnant
  • symptoms of pulmonary embolism
  • inadequate investigations



    • Independent blinded reference standard, applied in all patients from a consecutive appropriate spectrum.
    Reference standard:
    • venography in all patients with any positive test. Follow-up for three months if both tests negative
    Diagnostic test: whole blood agglutination: bedside d-dimer test performed by research nurse or technician- considered positive if any agglutination seen; impedance plethysmography (IPG)

    The evidence

    pre-test probability of deep vein thrombosis: 17.6%, (95% CI: 13.8% to 21.3%)

    diagnostic test deep vein thrombosis no deep vein thrombosis LR+
    (95% CI)    		 post-test probability LR-
    (95% CI)    		 post-test probability
    IPG+, d-dimer+ 39 3 60.9
    (19.4 to 192)     		93% 0.45
    (0.34 to 0.58)     		9%
    IPG+, d-dimer- 4 3 6.25
    (1.43 to 27.3)     		57% 0.95
    (0.90 to 1.01)     		17%
    IPG-, d-dimer+ 23 53 2.03
    (1.34 to 3.08)     		30% 0.80
    (0.68 to 0.95)     		15%
    either test positive 27 56 2.27
    (1.55 to 3.31)     		33% 0.74
    (0.61 to 0.90)     		14%
    IPG-, d-dimer- 4 269 0.070
    (0.027 to 0.18)     		1% 5.24
    (4.13 to 6.65)     		53%
    total 70 328


    diagnostic test DVT no DVT LR+
    (95% CI)    		 post-test probability LR-
    (95% CI)    		 post-test probability
    IPG 43 6 33.6
    (14.9 to 75.8)     		88% 0.39
    (0.29 to 0.53)     		8%
    total 70 328


    diagnostic test DVT no DVT LR+
    (95% CI)    		 post-test probability LR-
    (95% CI)    		 post-test probability
    d-dimer 62 56 5.19
    (4.03 to 6.68)     		53% 0.14
    (0.072 to 0.27)     		3%
    total 70 328

    Comments

    1. Ultrasound scan is more commonly used over IPG- would d-dimer offer the same benefits?

    Citation

    1. Ginsberg JS, Kearon C, Douketis J, et al: The use of d-dimer testing and impedance plethysmographic examination in patients with clinical indications of deep vein thrombosis. Archives of Internal Medicine 1997; 157: 1077-1081
    Contributor: Chris Ball and Clare Wotton, May 2000
    Reviewer:

    Clinical Question.
    Patient suspected DVT
    Intervention or Exposure d-dimer and impedance plethysmography
    Comparison venography
    Outcome diagnosis