Venous thromboembolism: prophylaxis: neurosurgery: heparin reduces thromboembolic events but increases bleeding

Clinical bottom line (level 1a)

  1. Patients undergoing neurosurgery who take unfractionated or low-molecular-weight heparin compared with placebo are less likely to have a thromboembolic event (NNT = 8 at 30 days) , but are more likely to bleed (NNH = 34 at 30 days) .
  2. There is no clear difference in death, pulmonary embolism or major bleeding between the two groups.
Iorio and Agnelli: Archives of Internal Medicine 2000; 160 : 2327-2332
Expires November 2003

The study

Systematic review of all randomised controlled trials of
  • Patients: undergoing neurosurgery
  • Intervention: unfractioned or low-molecular-weight heparin compared with placebo
  • Outcome: venous thrombolism, bleeding

Articles found in ? using Medline, 1966 to 1999 (search terms: not given ) and hand-searching meeting abstracts, reference lists of retrieved articles and contacting colleagues

Selection criteria: not given
Appraisal criteria: not given
Articles excluded if:
  • no objective diagnosis of venous thromboembolism


4 randomised controlled trials found - involving 1022 patients followed for 1-2 months. 3 used LMWH, 1 used unfractionated heparin.
Studies were not found to be significantly heterogeneous.

The evidence

Outcome Time to outcome CER OR
(95% CI)		 NNT
(95% CI)
venous thromboembolism 30 days 121/417
(29.0%)		 0.48
(0.35 to 0.66) 		8
(5 to 14)
proximal DVT 30 days 39/312
(12.5%)		 0.48
(0.28 to 0.83) 		16
(9 to 60)
any bleeding 30 days 15/511
(2.9%)		 2.06
(1.12 to 3.77) 		-34
(-230 to -18)
death, pulmonary embolism, major bleeding 30 days 24/511
(4.7%)		 1.6
(0.95 to 2.69) 		34
(NNT = 450 to infinity;
NNH = 14 to infinity)

Comments

  1. The systematic review fails to give details of the search strategy, selection or appraisal criteria. This combined with the fact that searching was limited to Medline, makes the results less certain.

Citation

  1. Iorio A, and Agnelli G: low-molecular weight and unfractionated heparin for prevention of venous thromboembolism in neurosurgery - a meta-analysis. Archives of Internal Medicine 2000; 160 : 2327-2332
Search Terms: in ACP Journal Club
Contributor: Chris Ball, November 2001
Reviewer:

Clinical Question.
Patient neurosurgery
Intervention or Exposure prophylactic heparin
Comparison placebo
Outcome venous thromboembolism, death, bleeding