Do Publicly Available Risk Calculators Apply to Adult Spinal Deformity Surgery?

Background/Objectives: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) and SpineSage^TM risk calculators are automated online tools to predict short-term complications for surgical procedures. The objective of this study was to assess the validity of ACS-NSQIP and SpineSage^TM risk calculators to predict short-term complications after adult spinal deformity (ASD) surgery. Methods: We included ASD patients who had surgery between 2017 and 2020 (≥5 levels, single-stage, posterior-only). Patient factors were entered into the risk calculators to generate probabilities for 30-day outcomes. Calibration and discrimination were assessed using Brier scores and C-statistics, respectively. Results: A total of 198 patients were included (67 male, 131 female) who underwent posterior spinal fusion for ASD surgery. The ACS-NSQIP risk calculator had strong calibration for all complications (Brier score < 0.09) except non-home discharge (Brier score 0.2). Discrimination was poor for all complications except surgical site infection (C-statistic 0.86), venous thromboembolism (C-statistic 0.84), and readmission (C-statistic 0.7). The SpineSage^TM risk calculator had strong calibration for all complications (Brier score < 0.09) aside from the "any complications" subset (Brier score 0.36). The discrimination capacity was poor for all complications (C-statistic < 0.7). Conclusions: The ACS-NSQIP calculator had strong calibration and poor discrimination for most complications. The SpineSage^TM calculator had strong calibration for most complications and a poor discrimination capacity for all complications. NSQIP calculation deficits may be due to the reliance on a single CPT code to calculate risk. The deficient discriminatory capacity of the SpineSage^TM calculator may be due to the inclusion of common perioperative occurrences as complications.