Venous thromboembolism: prophylaxis: total knee arthroplasty: LMWH and pneumatic compression are more effective than aspirin and warfarin

Clinical bottom line (level 2a)

  1. Patients undergoing total knee arthroplasty who take warfarin compared with aspirin are less likely to develop a symptomatic DVT (NNT = 8 at days) .
  2. Patients who take LMWH are less likely to develop a symptomatic DVT than patients on aspirin (NNT = 4 at days) or warfarin (NNT = 6 at days) .
  3. Patients who receive pneumatic compression are less likely to have a symptomatic DVT compared with those who receive aspirin (NNT = 4 at days) or warfarin (NNT = 6 at days) .
  4. There is no clear difference between LMWH and pneumatic compression.
Westrich et al: Journal of Bone and Joint Surgery (Br) 2000; 82 : 795-800
Expires November 2003

The study

Systematic review of all prospective studies of
  • Patients: undergoing total knee arthroplasty
  • Intervention: prophylaxis with aspirin, warfarin, LMWH or pneumatic compression
  • Outcome: venous thromboembolism

    Articles found in ?English using Medline, 1966 to December 1997 (search terms: thrombosis or embolism ) and searching citation lists of retrieved articles, and searching proceedings and abstracts from Orthopaedic Transactions and Thrombosis and Haemostasis

    Selection criteria: see above
    Appraisal criteria: detailed in text: prospective, randomisation, blinding, adequate treatment and follow-up
    Articles excluded if:
    • no objective diagnosis of DVT or PE


    23 studies involving 6001 patients found - 3214 receiving aspirin; 1203 warfarin; 1075 LMWH; 509 intermittent pneumatic compression

    The evidence

    Outcome Time to outcome CER OR
    (95% CI)    		 NNT
    (95% CI)
    warfarin v. aspirin: DVT days 1701/3214
    (52.9%)    		 1.7
    (1.5 to 1.9)     		8
    (7 to 10)
    LMWH v. aspirin: DVT days 1701/3214
    (52.9%)    		 3.47
    (3.04 to 3.96)     		4
    (3 to 4)
    pneumatic compression v. aspirin: DVT days 1701/3214
    (52.9%)    		 3.25
    (2.7 to 3.8)     		4
    (4 to 4)
    LMWH v. warfarin: DVT days 541/1203
    (45.0%)    		 1.9
    (1.6 to 2.3)     		6
    (5 to 9)
    pneumatic compression v. warfarin: DVT days 541/1203
    (45.0%)    		 2.05
    (1.76 to 2.39)     		6
    (5 to 7)
    pneumatic compression v. LMWH: DVT days 311/1075
    (28.9%)    		 1.09
    (0.9 to 1.33)     		55
    (NNT = 16 to infinity;
    NNH = 47 to infinity)

    Comments

    1. There were too few symptomatic PEs for significant odds ratios to be calculated

    Citation

    1. Westrich GH, Haas SB, Mosca P, et al: meta-analysis of thromboembolic prophylaxis after total knee arthroplasty. Journal of Bone and Joint Surgery (Br) 2000; 82 : 795-800
    Search Terms: from ACP Journal Club
    Contributor: Chris Ball, November 2001
    Reviewer:

    Clinical Question.
    Patient total knee arthroplasty
    Intervention or Exposure warfarin, aspirin, LMWH, pneumatic compression
    Outcome symptomatic DVT or PE