Deciding whether to undergo major surgery is a complex decision involving patients, their surgeons and anaesthetists.  

When clinicians talk about surgical risk, they’re referring to the balance of risk: weighing the short and long-term risks of surgery, against the overall benefits of the procedure. Accurately predicting a patient’s risk of death or complications after surgery is crucial for informed consent.  

In the past clinicians have found it difficult to provide their patients with a clear assessment of mortality risk because the tools available were old and created using clinical information from the US or the UK.  

What if there was a way New Zealanders could accurately predict the risk associated with major surgery? 

A highly accurate tool for New Zealanders to predict risk following surgery 

The nzRISK calculator is a pre-operative risk prediction tool developed specifically for the New Zealand population, using New Zealand data. It applies to all non-cardiac patients over the age of 18.  

The calculator was developed as part of an ongoing collaboration between Orion Health data scientists and local clinicians enabled by Precision Driven Health. The data used comes from New Zealand’s Ministry of Health and captures 99% of hospital admissions in New Zealand between 2011 – 2016.   

This work builds on the existing literature mostly by applying techniques to New Zealand-specific data. Technically, the model uses a form of penalised regression to construct the model which was chosen so that the outputs could be easily understood. 

Patients and clinicians can input various pieces of information, such as age, gender, ethnicity, type of procedure, and pre-existing conditions, and the nzRISK calculator will produce a mortality risk score for that patient at one month, one year and two years after surgery. 

nzRISK is a highly accurate tool for New Zealanders to predict their risk of death following surgery. The outcomes are wide-reaching, and it can be used to: 

  • Improve risk estimates needed for informed consent 
  • Improve the decision-making process 
  • Help with triaging of patients 
  • Quantify healthcare performance
  •  Avoid low-value operations 

nzRISK in use

Auckland City Hospital is one of the early users of nzRISK, where it has been incorporated into pre-operative processes. The tool simplifies the process for patients, so they can avoid unnecessary or repeat hospital visits. For clinicians, the tool improves efficiency, allowing them to spend more time with higher-risk patients, while also providing high-quality information for discussions. Predictive medicine to improve the patient experience – isn’t that the ideal? 

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See nzRISK Calculator in action