Accuracy of the Surgical Risk Preoperative Assessment System (SURPAS) in a broad, elderly (age ≥ 65) patient population.

Abstract

As more operations are performed on older adults, risk assessment for postoperative complications is important to inform patients and providers, especially because older patients have higher complication rates compared with younger patients. The Surgical Risk Preoperative Assessment System, a universal, parsimonious surgical risk calculator, has not yet been evaluated for accuracy in the older patient population. Data from the American College of Surgeons National Surgical Quality Improvement Program participant use file, 2009-2018, were used to develop the Surgical Risk Preoperative Assessment System models, and data from 2019 to 2020 were used to test the models in all, older, and younger patients. Multiple logistic regression was used with the Surgical Risk Preoperative Assessment System variables (operation Current Procedural Terminology code, American Society of Anesthesiologists class, functional health status, surgeon specialty, emergency status, inpatient or outpatient, and patient age) as independent variables and 12 common postoperative complications as dependent variables. C-indices, Brier scores, and Hosmer-Lemeshow calibration graphs were used for model evaluation. Developmental and testing data had sample sizes of 6,924,709 and 1,929,287, respectively. In the testing data, 37.7% of patients were older. The mean c-index across all outcomes for older patients was 0.800 vs 0.846 for younger patients. The c-index was good to fair (≥0.70) for 11 of the 12 assessed outcomes for the older group. The average Brier score was slightly higher (worse) for older versus younger patients (0.036 vs 0.019). Hosmer-Lemeshow graphs showed good calibration between older and younger patients. The performance of the Surgical Risk Preoperative Assessment System was slightly worse in older versus younger patients but was clinically acceptable.