Deep vein thrombosis: elective hip arthroplasty: some thromboembolism prophylaxis is more effective than others

Clinical bottom line (level 2a)

  1. Patients undergoing total hip arthroplasty who receive any thromboembolism prophylaxis are less likely to have a DVT than patients given placebo.
  2. Patients who receive LMWH, warfarin or pneumatic compression are less likely to have a pulmonary embolism than patients on placebo.
  3. Patients who receive LMWH or low-dose heparin are more likely to have minor bleeding than patients on placebo.
  4. Patients who receive low-dose heparin are more likely to have major bleeding than patients on placebo.
Freedman et al: J Bone Joint Surgery 2000; 82 : 929-938
Expires May 2004

The study

Systematic review of all randomised controlled trials of
  • Patients: undergoing elective total hip arthroplasty
  • Intervention: thromboembolic prophylaxis with unfractionated heparin, LMWH, warfarin, pneumatic compression, aspirin compared with other method of prophylaxis or placebo
  • Outcome: deep vein thrombosis (confirmed on bilateral venography)

Articles found in English using Medline, January 1966 to May 1998 (search terms: hip, hip arthroplasty, hip replacement, thrombosis, thromboembolism, pulmonary embolism, and prophylaxis ) and hand-searching own reference files and bibliographies of retrieved articles and selected reviews

Selection criteria: by 2 independent reviewers
Appraisal criteria: by 2 independent reviewers - disagreements were resolved by consensus: randomisation
Articles excluded if:
  • prophylaxis not started within 24 hours of surgery or not continued for at least 7 days
  • unable to separate patients receiving total hip arthroplasty from other groups
  • any combination of prophylactic agents except with graduated compression stockings
  • duplicate reports
52 RCTs were found involving 10929 patients
  • 21 studies involving 5512 patients receiving LMWH
  • 12 studies involving 1493 patients receiving warfarin
  • 8 studies involving 687 patients receiving aspirin
  • 11 studies involving 1859 patients receiving low-dose heparin
  • 5 studies involving 431 patients receiving pneumatic compression
  • 13 studies involving 947 patients receiving placebo

Studies were found to be heterogeneous for DVT and minor wound bleeding. Exclusion of outlying studies did not change the results though.

The evidence

outcome time to outcome number of patients/total number %
(95% CI)
LMWH: DVT ? 918/5512 17.7%
(14.5% to 21.4%)
warfarin: DVT ? 334/1493 23.2%
(19.3% to 27.7%)
aspirin: DVT ? 214/687 30.6%
(21.2% to 41.8%)
low-dose heparin: DVT ? 429/1859 31.1%
(22.7% to 40.9%)
pneumatic compression: DVT ? 94/431 20.7%
(14.6% to 28.7%)
LMWH: PE ? 19/5238 0.36%
(0.22% to 0.57%)
warfarin: PE ? 2/1232 0.16%
(0.02% to 0.59%)
pneumatic compression: PE ? 1/388 0.26%
(0.01% to 1.43%)
LMWH: minor bleeding ? 382/4064 10.5%
(5.9% to 17.8%)
low-dose heparin: minor bleeding ? 149/1453 13.5%
(8.3% to 21.2%)
low-dose heparin: major bleeding ? 69/1992 3.46%
(2.70% to 4.36%)

  • Only the outcomes for which the agents were significantly different from placebo were reported.

Comments

  1. By limiting the search to Medline and the English language, important articles may have been missed.

Citation

  1. Freedman KB, Brookenthal KR, Fitzgerald RH, et al: a meta-analysis of thromboembolic prophylaxis following elective total hip arthroplasty. J Bone Joint Surgery 2000; 82 : 929-938
Search Terms: from ACP Journal Club other articles noted
Contributor: Chris Ball, May 2002
Reviewer:

Clinical Question.
Patient total hip arthroplasty
Intervention or Exposure thromboembolism prophylaxis
Outcome deep vein thrombosis