Surgery is risky – more for some, and less for other patients. That is why it is important to be able to accurately assess a patient’s fitness and suitability for surgery, the problems he might develop, and the care he needs after. However, most available risk prediction methods that help surgeons and anaesthesiologists in their pre-surgical assessments have limitations as they were developed in the West, based on the Western world population and healthcare systems.
Realising this, a team of Singapore General Hospital (SGH) anaesthesiologists has come up with a surgical risk calculator that takes into account Singapore population’s environment, genetic makeup and healthcare systems.
The Combined Assessment of Risk Encountered in Surgery (CARES) calculator is the first of such tools developed for Singaporean patients. Not only is CARES more appropriate, but it is also easier to use as it requires only information that is routinely collected during patients’ pre-surgery assessments.
“With CARES, we can potentially do a better risk assessment and take necessary steps to mitigate some risks or plan for post-surgery care. CARES will also allow better discussions and shared medical decision making between patients and their doctors,” said Dr Hairil Rizal Abdullah, Clinical Director, Perioperative Services, and Consultant, Dept of Anesthesiology, SGH.
Dr Hairil Rizal and his team analysed the medical records of over 100,000 SGH patients, who had undergone surgery between January 2012 and October 2016. The data of these patients were then divided into two groups - one set was used to develop the CARES calculator, and the other, to validate the accuracy of the risk prediction tool. They found that CARES was able to predict risk of death as well as the need for close monitoring in the ICU following surgery with good accuracy. Furthermore, it performed better than the existing method of risk assessment.
Nine common health indicators are used in the calculator. These include age, anaemia, ischaemic heart disease, gender, the presence of congestive heart failure, and red cell distribution width (RDW) – a biomarker that was recently found to be able to predict death risk. A high RDW reflects irregular red blood cell sizes, which can indicate nutrient deficiency, inflammation, anaemia, or some other underlying condition.
The combined CARES score determines a patient’s risk – low, low-moderate, moderate-high or high. A score of more than 30 implies that the patient has a higher risk of death and requires ICU care post-surgery. Alternative surgical or non-surgical options could be considered in this case, and the patient should be prepared for ICU stay. On the other hand, a score of less than 10 indicates a low risk of the above.
To validate the usefulness of CARES in other institutions locally, Dr Hairil Rizal and his team are developing a web-based version of the calculator. The team is also currently working on increasing the ability of CARES to predict other individual complications such as heart attack, stroke and infections after surgery.
The study findings were published in BMJ Open
, a medical journal, in March 2018.