Development and validation of the Surgical Outcome Risk Tool (SORT)

Area of Science:

• Anesthesiology and Perioperative Medicine
• Surgical Outcomes Research
• Health Services Research

Background:

• Existing risk stratification tools for non-cardiac surgery have limitations and are not routinely used in clinical practice.
• Clinical experience indicates a need for improved preoperative risk assessment to predict patient outcomes.
• The National Confidential Enquiry into Patient Outcome and Death (NCEPOD) Knowing the Risk study provides a valuable dataset for developing such tools.

Purpose of the Study:

• To develop and validate a novel preoperative risk stratification tool to predict 30-day mortality after non-cardiac surgery in adults.
• To create a tool that is simple, rapid, and incorporates key predictive variables.
• To compare the performance of the new tool against existing risk stratification methods.

Main Methods:

• Analysis of a large dataset from the NCEPOD Knowing the Risk study, split into derivation and validation cohorts.
• Logistic regression modeling in the derivation cohort to identify significant risk factors for 30-day mortality.
• Development of the Surgical Outcome Risk Tool (SORT) based on six identified variables: ASA-PS grade, surgical urgency, surgical specialty, surgical severity, cancer, and age.

Main Results:

• A total of 16,788 patients were analyzed (11,219 in derivation, 5,569 in validation cohorts).
• The SORT model incorporated six key variables: ASA-PS grade, surgical urgency, high-risk surgical specialty, surgical severity, cancer, and age (≥65 years).
• In the validation cohort, SORT demonstrated superior discrimination (ROC AUC 0.91) compared to ASA-PS (0.87) and Surgical Risk Scale (0.88), with good calibration.

Conclusions:

• The Surgical Outcome Risk Tool (SORT) is a validated, accurate, and simple tool for predicting 30-day mortality after non-cardiac surgery.
• SORT utilizes six easily obtainable preoperative variables for rapid risk assessment.
• The tool provides a percentage mortality risk, enhancing preoperative decision-making and patient management.