P90. External validation of the ESSG-ISSG calculator utilizing a single institutional experience for adult spinal deformity corrective surgery

Abstract

BACKGROUND CONTEXT NSQIP Surgical Risk Calculator is a web-based decision aid and informed consent tool widely used by surgeons and their patients. This application creates patient-specific risks for those planning to undergo a procedure. Despite its wide use, minimal studies have validated the external applicability of the NSQIP calculator, in the setting of adult spinal deformity. PURPOSE Identify NSQIP risk calculator usability in a population of adult spinal deformity (ASD) patients from a single institution database (Quality). STUDY DESIGN/SETTING Retrospective cohort study of patients with adult spinal deformity between 2011-2018. PATIENT SAMPLE Adult spinal deformity patients. OUTCOME MEASURES Any Complication rate, cardiac complication, SSI, UTI, return to OR and length of stay (LOS). METHODS ASD patients were isolated in Quality (2011-2018). CPT codes for ASD patients were utilized in the NSQIP calculator in order to create baseline expectations for patient outcomes. 7 variables shared among Quality and NSQIP risk calculator were identified for average predictive values. The same perioperative outcomes collected from the NSQIP calculator was then analyzed in the Quality database. Pts were further stratified by frailty (not frail [NF] 0.5). Brier scores were calculated for each variable in order to validate the calculator's predictability in Quality. Having a score closer to 1 means the NSQIP calculator is not predictive of that specific outcome. A score closer to 0 means the NSQIP calculator was a predictive tool for that factor. RESULTS A total of 1,606 ASD patients were isolated from the Quality (48.7yrs, 63.8%F, 25.8 kg/m2). 33.4% received decompressions and 100% received a fusion. Of these Quality patients, 15.1% had past medical history of hypertension, 3.1% malignant cancer, 5.2% diabetes, 2.6% connective tissue disease and 2.8% chronic pulmonary disease. The average ASD outcome predicted by the NSQIP risk calculator predicted lower rates for NSQIP patients for return to OR (0.8% vs 2.4%), LOS (2.5d vs 6.5d), total complication rate (11.5% vs 16.5%), and cardiac (0.34% vs 1.9%) than Quality patients. The single institution did have lower UTI and SSI outcomes (1.7% vs 2.85%; 1% vs 1.8% respectively). The calculated Brier scores identified the calculator's predictability for each factor: complication total (0.78), cardiac (0.99), SSI (0.99), UTI (0.96), and return to OR (0.92). The only variable predictive among ASD patients was death with a Brier score of 0 in both groups. This was also the only factor among NF patients (Brier score:0). The NSQIP calculator predicted outcomes for F patients that were lower than those identified in the single institution and therefore, didn't have much usability in this population. CONCLUSIONS The NSQIP calculator is not a valid calculator in our single institutional database. It is unable to comment on surgical complications such as return to OR, SSI, UTI and cardiac that are typically associated with poor patient outcomes. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.