Extended VTE prophylaxis after major cancer surgery – the evidence

Posted 28 June 2013 in

Lesley Hunt, Consultant Surgeon
Presented at ACPGBI Liverpool 2013, 3 July

Acknowledgement:
Dr Rhona Maclean Consultant Haematologist, Sheffield Teaching Hospitals NHS Trust

Patients undergoing major surgery without venous thromboembolism (VTE) prophylaxis have a high risk of VTE, which are often symptomatic and occasionally fatal. Post operative VTE prophylaxis during hospitalisation is well established. But why give extended pharmacological prophylaxis to patients undergoing major cancer surgery?

NICE Guideline CG 92 Venous Thromboembolism – reducing the risk1 and its update recommends pharmacological VTE prophylaxis is given for 28 days post operatively after major abdominal and pelvic cancer surgery. This is based on 5 randomised trials and a Cochrane Meta Analysis2. The trials show that extending the duration of Low Molecular Weight Heparin (LMWH) prophylaxis to 28 days post operatively will result in a statistically significant reduction in proximal Deep Vein Thrombosis (DVT). Mortality benefit was not demonstrated, by the trials but collateral data suggest this will result in a small reduction in 90 day mortality. The number needed to treat to prevent a proximal DVT is 25 patients and to prevent a fatal pulmonary embolism is calculated as 250. Clearly this will only have a marginal benefit in terms of mortality reduction but, in well run units, this does represent a 10% mortality reduction after major colorectal resection.

It has been hoped that laparoscopic surgery and enhanced recovery programs would make VTE prophylaxis obsolete. But data from Meta Analysis of randomised trails shows that so far there is not the evidence to support treating these patients differently.

The cost of extended prophylaxis is low and may well turn out to be cost negative. Prevention costs of proximal DVT in Sheffield are about £140 per patient or £3500 per proximal DVT prevented. The cost of treating the initial episode is not so clearly defined but appears to exceed this in some cases. Long term cost benefits are at present incompletely understood.

Evidence Summary Level of Evidence
4% ↓ proximal DVT 1a
0.4% ↓ mortality 2
Laparoscopic cases at risk 1a
Easy + Cheap Sheffield Experience

Concerns have been expressed about the logistic difficulties of implementing this policy but centres such as Sheffield Teaching Hospitals NHS Trust, which have been doing it since 2011, have not experienced any significant problems. Furthermore, in 2012 The British Committee for Standards in Haematology removed the requirement to screen for Heparin Induced Thrombocytopenia in patients discharged home from hospital on LMWH. This really opens the door to wide scale implementation of extended prophylaxis.

  1. CG92 Venous thromboembolism – reducing the risk – NICE Guidance
    www.guidance.nice.org.uk
  2. Prolonged thromboprophylaxis with Low Molecular Weight heparin for abdominal and pelvic surgery. www.thecochranelibrary.com