Venous thromboembolism: prophylaxis: heparin and mechanical devices help prevent DVT following hip surgery.

Clinical bottom line (level 1a)

  1. Elderly patients who have undergone surgery for hip fractures and are given heparin (low molecular weight or unfractionated) are less likely to have a deep vein thrombosis than those not given heparin (NNT = 5 at unknown) , but there is no clear difference in mortality.
  2. Patients given mechanical devices (compression stockings, calf or foot pumps) are less likely to have a deep vein thrombosis than those not given them (NNT = 7 at unknown) .
Handoll et al: Cochrane library, Issue 3: Oxford Update Software 1998; 4: -
Expires May 2003

The study

Systematic review of randomised or quasi-randomised of
  • Patients: elderly patients undergoing surgery for proximal hip fractures
  • Intervention: heparin (low molecular weight or unfractionated) and mechanical devices (compression stockings, calf or foot pumps) compared with
  • Outcome: deep vein thrombosis or pulmonary embolism after surgery


    • Articles found in all using MEDLINE. CINAHL, EMBASE, up to September 1996 (search terms: detailed in text ) and reference lists checked, colleagues and trialists contacted. English language journals on musculoskeletal topics handsearched

    Selection criteria: as above
    Appraisal criteria: two independent reviewers assessed the trials using set criteria
    Articles excluded if: none given

    26 trials were included

    The evidence

    heparin/LMWH
    Outcome Time to outcome CER OR
    (95% CI)    		 NNT
    (95% CI)
    deep vein thrombosis unknown 203/519
    (39.1%)    		 0.41
    (0.31 to 0.55)     		5
    (4 to 8)
    death unknown 35/423
    (8.27%)    		 1.39
    (0.86 to 2.23)     		-35
    (NNT = 93 to infinity;
    NNH = 12 to infinity)
    deep vein thrombosis with mechanical devices unknown 42/212
    (19.8%)    		 0.24
    (0.13 to 0.44)     		7
    (6 to 10)

    Comments

    1. There was insufficient information to address pulmonary embolism, complications, length of hospital stay and mortality.
    2. Trials were noted to be poor for the following reasons:
      • lack of power
      • incomplete information on patients or important outcomes (eg. none reported on post-thrombotic leg)
      • limited follow-up
      • poor internal validity

    Citation

    1. Handoll HHG, Farrar MJ, McBirnie J, et al: Heparin, low molecular weight heparin and physical methods for preventing deep vein thrombosis and pulmonary embolism following surgery for hip fractures (Cochrane Review). Cochrane library, Issue 3: Oxford Update Software 1998; 4: -
    Search Terms: venous thromboembolism in Cochrane
    Contributor: Chris Ball and Clare Wotton, May 2000
    Reviewer:

    Clinical Question.
    Patient undergone surgery
    Intervention or Exposure heparin and mechanical devices
    Comparison placebo or no treatment
    Outcome deep vein thrombosis or pulmonary embolism