Introduction: The American College of Surgeons NSQIP Surgical Risk Calculator (SRC) was a tool developed to use 21 individual patient characteristics to make predictions for occurrence of 13 general and 2 procedure specific outcomes. Literature on the role of NSQIP SRC in spine surgery is sparse.
Methods: The American College of Surgeons (ACS) National Surgical Quality Improvement Project (NSQIP) user file for 2015 was queries for patients above the age of 18 undergoing single level posterior lumbar fusion surgery. Individual patient characteristics were entered into the online risk calculator interface to retrieve the predicted estimated risk for perioperative outcomes and complications including surgical site infection, readmissions, reoperations, major complication, any complication and mortality. Following this, predictive performance was analyzed by computing brier score, c-statistic and sensitivity values for all observed outcomes.
Results: A total of 2808 patients were included in the analysis with 53.7% (1510) females. Overall, a very low incidence of 30-day postoperative complications was observed with the procedure (0.9%-6.3%). Poor predictive performance was found for all outcomes including readmissions (c-statistic=0.63, sensitivity=15.28%, brier score=0.048) and returns to OR (c-statistic=0.63, sensitivity=15.28%, brier score=0.048). The best performance was observed for venous thromboembolism (c-statistic=0.66, brier score=0.008) although sensitivity was poor (3.85%) on account of low incidence. Predictive performance for length of stay revealed good agreement between observed and predicted values with the exception of prolonged predicted hospital stays (>3.5 days).
Conclusions: To the best of our knowledge, this is the first study which has assessed the performance of the NSQIP-SRC for a homogenous population of patients undergoing a single level posterior lumbar fusion. Although the calculator did not fare well in predicting most outcomes, results need to be interpreted in the context of the low incidence rate of such outcomes.
Patient Care: This study will evaluate the predictive performance of the American College of Surgeons- Surgical Risk Calculator in patients undergoing lumbar fusion. This validation will help spine surgeons understand whether generalized risk prediction models are really useful and address need for development of specialty specific risk prediction models.
Learning Objectives: 1) Characterizing predictive performance of the NSQIP-Surgical Risk Calculator for patients undergoing posterior lumbar fusion
2) Utility of risk prediction models in spine surgery
3) Methods to validate predictive models