Venous thromboembolism: prophylaxis: major trauma: LMWH was more effective than heparin.

Clinical bottom line (level 1b)

  1. In men with major trauma admitted for more than seven days, low molecular weight heparin prevented more deep vein thromboses than heparin (NNT = 9 at 14 days) .
  2. There was no clear effect on pulmonary embolism or major bleeds.
Geerts et al: New England Journal of Medicine 1996; 335 (10): 701-707
Expires September 2003

The study

Double-blinded concealed randomised trial with intention-to-treat
Setting: level one trauma centre, Canada

344 patients (aged range 15 to 45 years, 99% male) admitted with major trauma

Excluded if
  • injury score <9
  • unlikely to survive or discharged within seven days
  • frank intracranial bleeding on CT (not excluded if cerebral contusion, localised petechial haemorrhage or diffuse axonal damage)
  • bleeding uncontrolled for 36 hours post-injury
  • systemic coagulopathy; PT>3 seconds control, platelets <50
  • pregnant
  • history of allergy to contrast media
  • renal failure with creatinine >300
  • no venous access if amputation of major foot injury preventing venography
  • need for therapeutic anticoagulation


    • Control Group: (n = 173, 173 analysed): heparin 5000 units every 12 hours, given within 36 hours of injury, for 14 days
    Experimental Group: (n = 171, 171 analysed): enoxaparin 30 mg every 12 hours, within 36 hours of injury, for 14 days

    100% followed for 14 days
    Outcome notes:
    • deep vein thrombosis : venogram between day 10 and 14 of admission or before discharge. If DVT suspected, ultrasound was performed
    • pulmonary embolism : diagnosed by ventilation-perfusion scan if clinical signs. If results indeterminate, they had a pulmonary angiography or contrast venogram or venous ultrasound.
    • major bleed : overt fall in Hb>2 g/dl; transfusion of two or more units of packed red cells; intracranial or retroperitoneal bleed; need for surgical intervention

    The evidence

    Outcome Time to outcome CEREERRRR
    (95% CI)    		ARR
    (95% CI)    		NNT
    (95% CI)
    deep vein thrombosis 14 days 60
    (34.7%)    		 40
    (23.4%)    		 33%
    (5% to 52%)    		 11.3%
    (1.77% to 20.8%)    		 9
    (5 to 56)
    pulmonary embolism 14 days 0
    (0.00%)    		 1
    (0.58%)    		 %
    (% to %)    		 -0.58%
    (-1.73% to 0.56%)    		 -171
    (NNT = 179 to infinity;
    NNH = 58 to infinity)
    major bleed 14 days 1
    (0.58%)    		 5
    (2.92%)    		 -406%
    (-4200% to 40%)    		 -2.35%
    (-5.11% to 0.42%)    		 -43
    (NNT = 238 to infinity;
    NNH = 20 to infinity)

    Comments

    1. The study was too small to comment on differences in pulmonary embolism rate and major bleeding.
    2. Unclear how many DVTs were symptomatic.

    Citation

    1. Geerts WH, Jay RM, Code KI, et al: A comparison of low-dose heparin and low-molecular-weight heparin as prophylaxis against venous thromboembolism after major trauma. New England Journal of Medicine 1996; 335 (10): 701-707
    Contributor: Chris Ball and Clare Wotton, May 2000
    Reviewer:

    Clinical Question.
    Patient major trauma
    Intervention or Exposure heparin
    Comparison low molecular weight heparin
    Outcome DVT, PE, major bleed