Deep vein thrombosis: prevention: compression stockings and LMWH are more effective than stockings alone.

Clinical bottom line (level 1b)

  1. Patients undergoing elective neurosurgery who wear compression stockings and have enoxaparin, are less likely to have symptomatic pulmonary embolism or deep vein thrombosis than patients who just wear compression stockings (NNT = 16 at 60 days) .
  2. Patients given perioperative enoxaparin are less likely to get any pulmonary embolism or deep vein thrombosis (NNT = 6 at 60 days) .
  3. The effect of perioperative enoxaparin on major or minor bleeding and mortality is unclear.
Agnelli et al: New England Journal of Medicine 1998; 339 (2): 80-85
Expires May 2003

The study

Double-blinded concealed randomised trial without intention-to-treat
Setting: neurosurgical units in seven acute hospitals, Italy

307 patients (aged mean 56 years, 50% male) undergoing elective cranial or spinal surgery

Excluded if
  • <18 years old
  • <40 kg or >120 kg in weight
  • abnormal operative bleeding
  • bleeding disorder (PT>30% control or platelet <100 000)
  • need for therapeutic anticoagulant or antiplatelet therapy
  • allergy to contrast media
  • renal failure (creatinine >180 mmol/dl)
  • likely to be in hospital <7 days
  • pregnant


    • Control Group: (n = 154, 130 analysed): placebo given s/c for 8 +/- 1 days
    Experimental Group: (n = 153, 130 analysed): enoxaparin 40 mg subcutaneously on the morning following the surgery and continued daily for 8 +/- 1 days
    All patients wore thigh-length compression stockings from the morning of the surgery until discharge. All patients had bilateral venography on about day eight.
    85% followed for 60 days
    Outcome notes:
    • symptomatic venous thromboembolism : DVT diagnosed on ultrasound scan and confirmed venographically. PE diagnosed by high-probability perfusion scan, or pulmonary angiogram if the scan was non-diagnostic
    • major bleed : clinically overt and a fall in haemoglobin >2 g/dl or transfusion of =2 units; or intracranial or retroperitoneal bleeding
    • minor bleed : surgical wound hematoma, hematuria, injection-site hematoma, anaemia without clinically obvious bleeding

    The evidence

    Outcome Time to outcome CEREERRRR
    (95% CI)    		ARR
    (95% CI)    		NNT
    (95% CI)
    symptomatic venous thromboembolism 60 days 9
    (6.92%)    		 1
    (0.77%)    		 89%
    (14% to 99%)    		 6.15%
    (1.54% to 10.8%)    		 16
    (9 to 65)
    deep vein thrombosis or pulmonary embolism 60 days 43
    (33.1%)    		 22
    (16.9%)    		 49%
    (20% to 67%)    		 16.2%
    (5.81% to 26.5%)    		 6
    (4 to 17)
    major bleed 60 days 4
    (3.08%)    		 4
    (3.08%)    		 0%
    (-291% to 74%)    		 0.00%
    (-4.20% to 4.20%)    		 inf
    (NNT = 24 to infinity;
    NNH = 24 to infinity)
    minor bleed 60 days 7
    (5.38%)    		 14
    (10.8%)    		 -100%
    (-379% to 17%)    		 -5.38%
    (-12.0% to 1.21%)    		 -19
    (NNT = 83 to infinity;
    NNH = 8 to infinity)
    death 60 days 6
    (4.62%)    		 5
    (3.85%)    		 17%
    (-166% to 74%)    		 0.77%
    (-4.12% to 5.66%)    		 130
    (NNT = 18 to infinity;
    NNH = 24 to infinity)

  • Three patients in the placebo group had a pulmonary embolism.

    • Comments

    1. Careful patient selection for use of enoxaparin elective neurosurgery may be critical in minimizing the risk of bleeding
    2. Very low power to detect differences in death and bleeding.

    Citation

    1. Agnelli G, Piovella F, Buoncristiani P, et al: Enoxaparin plus compression stockings compared with compression stockings alone in the prevention of venous thromboembolism after elective nuerosurgery. New England Journal of Medicine 1998; 339 (2): 80-85
    Search Terms: hand search
    Contributor: Chris Ball and Clare Wotton, May 2000
    Reviewer: Janice L Zimmerman

    Clinical Question.
    Patient undergoing elective cranial or spinal surgery
    Intervention or Exposure enoxaparin with compression stockings
    Comparison compression stockings alone
    Outcome venous thromboembolism