This site has not been optimised for Internet Explorer due to Microsoft no longer providing support for the browser. Please view this site using another browser such as Google Chrome or Microsoft Edge.
Te Pū rauemi KOWHEORI-19 COVID-19 resource hub

Support for people working in health during the COVID-19 pandemic. Find information about how you can support yourselves and others, including consumers, teams and colleagues which complements and aligns with Ministry of Health resources.

Kia āta kōwhiri Choosing Wisely

The Choosing Wisely campaign seeks to reduce harm from unnecessary and low-value tests and treatment.

Thrombosis is a blood clot that forms in an artery or vein and is responsible for the world’s top three cardiovascular killers: heart attacks, strokes and venous thromboembolism (VTE). VTE most commonly occurs as deep venous thrombosis in a leg, but can also lead to a pulmonary embolism (PE) in the lungs, killing some 500,000 people a year in Europe, 25,000 of them in the United Kingdom alone. Hospital patients are particularly vulnerable.

A 2012 Commission-sponsored project to establish a national policy framework for VTE estimated around 2000 patients a year suffered a hospital-associated VTE event in New Zealand, a third of which would be PEs, with some 60 deaths.

The risk of VTE increases 10-fold in patients admitted to hospital with contributing factors including general ill health or comorbidities, reduced mobility, smoking, and poor fluid intake. Major surgical procedures (particularly orthopaedic and other high-risk surgeries) are further risk factors – however, patients who had short or minor procedures have also developed fatal PE, so no patient is automatically excluded from risk of VTE.

Preventing VTE in hospital patients is widely recognised internationally as a major opportunity to improve patient safety. A retrospective study at a large New Zealand hospital showed that 106 patients were harmed by hospital-associated VTE in 2008. In the same hospital, data collected over 2010 and 2011 found that more than 150 patients per year developed hospital-associated VTE.[1]

If these figures are extrapolated across the 20 district health boards (DHBs), they suggest more than 1500 patients a year may develop hospital-associated VTE. Morbidity from VTE for survivors and the resulting costs to the health care system can be substantial.

In a broad range of patients, effective VTE prevention techniques, such as drinking a recommended amount of water, keeping active, wearing compression stockings, appropriate medication in consultation with a surgeon, and mechanical prophylaxis techniques, can reduce the risk of DVT and both fatal and non-fatal PE by more than 60 percent.[2]

For more detailed information for health professionals see the NZ VTE Prevention Steering Group’s National policy framework: VTE prevention in adult hospitalised patients in NZ. June 2012. 



  1. Haematology Department, Counties Manukau District Health Board. Retrospective evaluation of hospital-acquired VTE rates at Counties Manukau DHB. (Unpublished report). 2008.
  2. Geerts W. Prevention of venous thromboembolism: a key patient safety priority. J Thromb Haemost. 2009;7(1):1-8.
Last updated: 16th December, 2021