Patient- and Hospital-level Factors Associated with Increased Admission Costs After Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis

Introduction: There is a paucity of studies assessing patient and hospital factors for increased costs in patients with adolescent idiopathic scoliosis (AIS) undergoing posterior spinal fusion (PSF). The goal of this study was to determine risk factors contributing to increased costs in patients with AIS undergoing PSF.

Methods: A retrospective cohort study was performed using the 2016-2019 National Inpatient Sample database. All AIS patients (10-17 years old) undergoing PSF, identified using ICD-10-CM coding, were categorized by cost, with increased costs defined as total costs of admission >75th percentile for the cohort (>$66,690). Demographics, comorbidities, operative variables, adverse events (AEs), length of stay (LOS), and costs were assessed. Multivariate analyses identified independent predictors of increased costs.

Results: Of the 17,615 study patients, 4,405 (25.0%) had an increased cost of admission, with the average cost close to double that of the Normal-Cost cohort (Normal Cost:$44,566±12,009 vs. Increased Cost:$89,458±24,659,p < 0.001). The Increased-Cost cohort had a greater proportion of patients with one or more comorbidities (p=0.042). The proportion of patients undergoing fusion of ≥8 thoracic levels (Normal Cost:73.0% vs Increased Cost:86.0%,p < 0.001) or experiencing any postoperative AE (Normal Cost:30.1% vs Increased Cost:38.9%,p=0.011) were significantly greater in the Increased-Cost cohort. The mean LOS was significantly greater in the Increased-Cost cohort (Normal Cost:3.61±1.47 days vs Increased Cost:4.72±4.47 days,p < 0.001). On multivariate analysis, Hispanic ethnicity [OR:1.46,p=0.013], Asthma [aOR:1.35,p=0.048], preoperative vitamin D deficiency [aOR:2.85,p=0.002], Medium hospital bed size [aOR:2.05,p=0.006], receiving treatment in a hospital in the West region [aOR:2.48,p=0.002], intraoperative electrophysiological monitoring [aOR:1.55,p=0.005], fusion of ≥8 thoracic levels [aOR:2.23,p < 0.001], experiencing 1 AE [aOR:1.48,p=0.011], and increased LOS [aOR:1.31,p < 0.001] were each independently associated with increased costs, while female sex [aOR: 0.69,p < 0.001] and Large hospital bed size [aOR: 0.39,p < 0.001] were associated with decreased costs.

Conclusion : Our study identifies multiple patient- and hospital-level factors for increased hospital costs after PSF for AIS.