Personal patient data improves surgery success

By December 9th, 2009

Australian surgeons are leading the world in using a new statistical model that predicts an individual patient's chances of success for a common type of vascular surgery and guides patient care.

Developed by CSIRO and the Royal Australasian College of Surgeons, the model – called the endovascular aneurysm repair risk assessment model (ERA) – is for the surgical treatment of aneurysm, a life-threatening weakness of an artery wall.

CSIRO statistician, Mary Barnes, said only eight factors are required to predict an individual’s surgical outcome.

“We put the eight variables into a simple spreadsheet that surgeons can find on our project website and use it to enter data and predict outcomes for an individual patient,” Mrs Barnes said.

“Variables like patient age and gender, aneurysm diameter and level of creatinine in the blood are examples of factors that determine how well a patient might respond to surgery.

“The ERA model processes the data and alerts the surgeon to any likely post-operative complications for that particular patient, so they can decide, for example, whether to undertake the surgery or use different treatments.

“It’s essentially personalised medicine.”

The ERA model was developed initially using Australian data from 961 patients, collected from the Royal Australasian College of Surgeons’ audit of aneurysm surgery to assess the short- to mid-term consequences of the surgery – then a relatively new procedure. 

“For aneurysm patients, the model is helping improve the quality of their medical treatment with just a bit of extra information”

Dr Rob Fitridge

The model was recently validated with data from St George’s Vascular Unit in London.
Project leader, Associate Professor Rob Fitridge of the Queen Elizabeth Hospital in Adelaide, said aneurysm surgery is very common – almost 1800 patients a year in Australia are treated, usually by implanting a stent.

“It’s important to understand the risk factors to get a good outcome well before a patient gets anywhere near an operating theatre,” Dr Fitridge said.

“For aneurysm patients, the model is helping improve the quality of their medical treatment with just a bit of extra information.”

The project, now managed through the University of Adelaide, recently attracted a five-year National Health & Medical Research Council grant to further improve and evaluate the model.

Mrs Barnes said the model has gained international interest and Australian vascular surgeons undertaking this kind of surgery will be invited to trial it.

“While some surgeons were initially sceptical that a simple data tool could help their work, we’ve had more than 250 downloads of the spreadsheet in about two years and the feedback has been very positive,” Mrs Barnes said.

She said that there was the potential to make similar models for other types of surgery or treatments as long as there is enough good data to analyse.

Mrs Barnes presented a paper on the model: ‘Personalised medicine: endovascular aneurysm repair risk assessment model using preoperative variables’, during last week’s International Biometric Society Australasian Region Conference 2009, in Taupo, New Zealand.

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