Increasing Cost Efficiency in Adult Spinal Deformity Surgery: Identifying Predictors of Lower Total Costs.

STUDY DESIGN Retrospective study of a prospective multicenter database. OBJECTIVE The purpose of this study was to identify predictors of lower total surgery costs at 3 years for Adult Spinal Deformity (ASD) patients. SUMMARY OF BACKGROUND DATA ASD surgery involves complex deformity correction. METHODS Inclusion criteria: surgical ASD (scoliosis≥20°, SVA≥5 cm, PT≥25°, or thoracic kyphosis ≥60°) patients >18 years. Total costs for surgery were calculated using the PearlDiver database. Cost per quality adjusted life year was assessed. A Conditional Variable Importance Table used non-replacement sampling set of 20,000 Conditional Inference trees to identify top factors associated with lower cost surgery for low (LSVA), moderate (MSVA), and high (HSVA) SRS Schwab SVA grades. RESULTS 316/322 ASD patients met inclusion criteria. At 3Y follow up, the potential cost of ASD surgery ranged from $57,606.88 to $116,312.54. The average costs of surgery at 3 years was found to be $72,947.87, with no significant difference in costs between deformity groups (p > 0.05). There were 152 LSVA patients, 53 MSVA patients, and 111 HSVA patients. For all patients, the top predictors of lower costs were frailty scores 1.5, baseline (BL) ODI 1.5, age <64, were the top predictors of lower costs (all p < 0.05). Among MSVA patients, ASD invasiveness scores <94.16, no past history of cancer, and frailty scores <0.3 trended towards lower total costs (p = 0.071, p = 0.210). For HSVA, no history of smoking and BMI <27.8 trended towards lower costs (both p = 0.060). CONCLUSIONS ASD surgery has the potential for improved cost efficiency, as costs ranged from $57,606.88 to $116,312.54. Predictors of lower costs included higher baseline SRS activity, decreased frailty, and not having depression. Additionally, predictors of lower costs were identified for different baseline deformity profiles, allowing for the optimization of cost efficiency for all patients.Level of Evidence: 3.