Abstract
INTRODUCTION: Substantial increase of costs in the surgical treatment of adult spinal deformity has given precedence to scrutinize the value it can provide hence cost-effectiveness (CE) is a vital analytical constituent. The analysis of factors associated with the durability of cost-effectiveness at 5 years has not been previously evaluated. METHODS: Adult spinal deformity (ASD) patients with baseline (BL) to 5-year (5Y) data were included. Cost calculation using PearlDiver database and CMS.gov definitions was used. Cost analysis was based on average DRG reimbursement rates. ODI was converted to SF-6D, with a 3% discount applied for residual decline in life expectancy. Cost per QALY gained at 2Y and 5Y was calculated. Threshold value for cost per QALY was $100,000. Patients that met 2Y (CE2+) were grouped based on meeting CE at 5Y(CE5+) or not(CE5-). Analysis based on meeting cost-effectiveness (CE) at 2Y and 5Y was conducted. Conditional-inference-tree (CIT) established cutoffs values for HRQLs. RESULTS: 299 patients with 5Y data were included. Major and minor complication rates were 11% and 47% respectively, while 26% underwent reoperation by 5Y. The mean cost of surgery was $91,095 ± $47,003, utility-gain of 0.091 ± 0.086, and QALY of 0.171 ± 0.183, CE of $118,976 ± $208,323. 85.5% of the cohort met CE at 2Y, 79.2% at 5Y, whereas 59.6% met both. Frailty was comparable at baseline but was worse in CE5- at 2Y. CIT depicted 2Y ODI < 18 and SRS-22r > 3.3 (both p < 0.03) being associated with higher rates of C5+. Multivariable-regression depicted higher baseline CCI and pelvic tilt (PT) to be the strongest baseline predictors of not maintaining CE at 5Y (CCI OR: 1.821, p = 0.009) (PT OR: 1.079, p = .030). CONCLUSIONS: The majority that met cost-effectiveness at the 2 year went on to maintain it at 5 years. Lower baseline CCI and PT were strong predictive factors.
Published Version
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