eMJA: Rational thromboprophylaxis in medical inpatients: not quite there yet

To the Editor: In the 3 November 2008 issue of the Journal, Millar recommends against routine thromboprophylaxis in medical patients.1

The evidence base for clinical decision making regarding thromboprophylaxis in medical patients remains limited. Although its overall benefit may be low, the absolute benefit to the community is significant. As up to 40% of cases of venous thromboembolism (VTE) occur in patients recently hospitalised for medical illness,2-3 there is a significant burden of disease that justifies prophylaxis in patients at high risk of VTE.

The challenge is to identify medical patients at greatest risk of VTE, and to provide appropriate pharmacological prophylaxis, but to avoid using prophylaxis in patients at lower risk of VTE.

Millar states that aspirin is as effective as heparin, with reference to the Pulmonary Embolism Prevention (PEP) trial.4 However, the PEP trial compared aspirin with placebo, and many participants also received heparin — it did not compare aspirin with heparin. Participants were undergoing surgery for hip fracture, and none were medical patients.

A reduction in the endpoint of fatal pulmonary embolus (PE) is difficult to demonstrate in trials where imaging is used to detect disease at an early stage. This prompts treatment of asymptomatic deep vein thrombosis and modifies the natural history, leading to low reported PE rates.

Rather than recommend for or against routine thromboprophylaxis in medical patients, we advise that patients should have a VTE risk assessment and that appropriate prophylaxis should be given according to evidence-based guidelines such as those of the American College of Chest Physicians5 and the International Consensus Statement6 (which we have attempted to summarise and condense into a practical, pocket-sized booklet7).

Competing interests: All authors are members of the Australia and Zealand Working Party on the Management and Prevention of Venous Thromboembolism. John Fletcher has received speaker fees and travel assistance from Sanofi-Aventis and GlaxoSmithKline, and a speaker fee from Bayer Schering Pharma. Donald MacLellan has received non-directed educational grants from a number of pharmaceutical and non-pharmaceutical companies, including Sanofi-Aventis, to allay costs in the production of the Prevention of venous thromboembolism booklets. Harry Gibbs has received clinical trial funding, consultancy fees, honoraria and travel grants from a number of pharmaceutical and medical device companies, including Sanofi-Aventis, Pfizer and Boehringer Ingelheim. Geoff Matthews received travel assistance from Sanofi-Aventis.

John P Fletcher, Professor of Vascular Surgery1Donald MacLellan, Director of Surgery2Harry Gibbs, Vascular Physician3Geoff Matthews, Vascular Physician4

1 Western Clinical School, Westmead Hospital, Sydney, NSW.

2 NSW Health, Sydney, NSW.

3 Princess Alexandra Hospital, Brisbane, QLD.

4 Austin and Repatriation Medical Centre, Melbourne, VIC.

johnfATmed.usyd.edu.au

Millar JA. Rational thromboprophylaxis in medical inpatients: not quite there yet. Med J Aust 2008; 189: 504-506. <eMJA full text> <PubMed>
Heit J, O’Fallon M, Petterson T, et al. Relative impact of risk factors for deep vein thrombosis and pulmonary embolism. Arch Intern Med 2002; 162: 1245-1248. <PubMed>
National Institute of Clinical Studies. The incidence and risk factors for venous thromboembolism in hospitals in Western Australia 1999 to 2001. Prepared by the School of Population Health, University of Western Australia. Melbourne: NICS, 2005.
Prevention of pulmonary embolism and deep vein thrombosis with low dose aspirin: Pulmonary Embolism Prevention (PEP) trial. Lancet 2000; 355: 1295-1302. <PubMed>
Geerts WH, Bergqvist D, Pineo GF, et al; American College of Chest Physicians. Prevention of venous thromboembolism: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th edition). Chest 2008; 133 (6 Suppl): 381S-453S.
Cardiovascular Disease Educational and Research Trust; Cyprus Cardiovascular Disease Educational and Research Trust; European Venous Forum; International Surgical Thrombosis Forum; International Union of Angiology; Union Internationale de Phlébologie. Prevention and treatment of venous thromboembolism. International Consensus Statement (guidelines according to scientific evidence). Int Angiol 2006; 25: 101-161. <PubMed>
Australia and New Zealand Working Party on the Management and Prevention of Venous Thromboembolism. Prevention of venous thromboembolism: best practice guidelines for Australia and New Zealand. 4th ed. Sydney: Health Education and Management Innovations, 2007.

(Received 3 Dec 2008, accepted 10 Feb 2009)

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