Deep vein thrombosis: LMWH prevented DVT in patients wearing plaster casts.

Clinical bottom line (level 1b)

  1. In patients wearing plaster casts for sprain or fractures of the leg, low-molecular-weight heparin prevented deep vein thrombosis.
Kock et al: Lancet 1995; 346: 459-461
Expires December 2003

The study

Unblinded concealed randomised trial with intention-to-treat
Setting: trauma outpatient clinic, Germany

339 patients (aged range 18 to 64 years; mean 34, 65% male) leg injuries and wearing below knee or cylinder casts.

Excluded if
  • prior DVT
  • pregnant
  • clotting disorder/anticoagulant medication
  • bleeding
  • chronic venous insufficiency
  • heparin contraindication
  • plaster cast post-surgery


    • Note:
  • Patients were stratified for varicose veins and obesity.
  • Leg immobilsation was between 2 and 72 days (mean 19).
  • Patients were followed until the plaster cast was removed.


    • Control Group: (n = 163, 163 analysed): no intervention
    Experimental Group: (n = 176, 176 analysed): low-molecular-weight heparin monoembolex 32 mg subcutaneously once daily

    100% followed for ?
    Outcome notes:
    • deep vein thrombosis : excluded before treatment by ultrasound and venogram if ultrasound uncertain. DVT reassessed when cast removed.

    The evidence

    Outcome Time to outcome CEREERRRR
    (95% CI)    		ARR
    (95% CI)    		NNT
    (95% CI)
    deep vein thrombosis 19 days 7
    (4.29%)    		 0
    (0.00%)    		 100%
    (% to %)    		 4.29%
    (1.18% to 7.41%)    		 23
    (14 to 85)

    Outcome Control Group
    (SD)    		 Experimental Group
    (SD)    		 Mean Difference
    (95% CI)
    days in plaster 18.8
    (13.0)     		15.2
    (12.0)     		3.6
    (0.9 to 6.3)

    Comments

    1. Low-molecular-weight heparin group wore casts for a shorter time- may explain why there were fewer DVTs. Uncertain whether DVTs were symptomatic or significant.
    2. Casts were applied for sprains (74%) and fractures (21%)- ?overuse of casts. If patients with fractures alone were studied would DVT rate be higher?
    3. Is heparin as effective?
    4. The lack of blinding may have significantly affected ultrasound diagnosis

    Citation

    1. Kock H-J, Schmit-Neuerburg KP, Hanke J, et al: Thromboprophylaxis with low-molecular-weight heparin in outpatients with plaster-cast immobilisation of the leg. Lancet 1995; 346: 459-461
    Contributor: Chris Ball and Clare Wotton, June 2000
    Reviewer: Alex Gallus

    Clinical Question.
    Patient leg injuries
    Intervention or Exposure LMWH
    Comparison no intervention
    Outcome DVT