Clinical decision making informed by science.

nzRISK is a pre-operative risk prediction tool providing an estimate for the risk of death at one month, one and two years following surgery. It has been developed and validated for patients in New Zealand, over the age of 18, undergoing non-cardiac surgery.



Prior to surgery, patients and clinicians decide whether to proceed, partly determined by the balance of risk and benefits. In addition to clinical assessment, risk assessment tools can help to inform these decisions.

nzRISK has been developed to be a simple and easy to use risk calculator based on the New Zealand population. It has been compiled using data from over 270,000 patients aged 18 or over undergoing non-cardiac surgery. It includes eight risk factors that can be entered below to give a 30 day, one and two year estimate of mortality. Each risk factor is associated with mortality and improves the performance of the calculator.

For more information see the publication in the British Journal of Surgery or the videos for medical professionals and patients. The nzRISK tool is available on this website for personal use only.


This work was developed by clinicians at Auckland City Hospital, through the Precision Driven Health research partnership with the support of the Perioperative Mortality Review Committee, Ministry of Health, New Zealand.


ASA-PS (American Society of Anaesthesiology – Physical Status) Score

  1. Normal healthy patient
  2. Patient with mild systemic disease
  3. Patient with severe systemic disease
  4. Patient with severe systemic disease that is a constant threat to life
  5. Patient who is moribund and not suspected to survive without the operation

Active malignancy

Cancer that is being actively treated, recurrent, metastatic or inoperable. This definition excludes squamous skin cancer and basal cell carcinoma.