Introduction: Surgery can be an effective intervention for adult spinal deformity (ASD) but it is expensive and associated with a high complication rate. This study aims to analyze the cost-effectiveness of ASD surgery, with age and baseline disability as key variables.
Methods: Decision-analytic models were constructed to assess three treatment strategies: Operative, Non-operative, and Non-operative with delayed surgery for non-responsive patients. Model inputs were derived from prospective registry data and published literature, and modeled stochastically. Equivalent decision trees but with different parameter values were constructed for six patient subgroups categorized by age (“younger” group: mean age 50 vs. “older” group: mean age 70), and disability level (low: ODI < 20, moderate ODI 20-40, high ODI >40). 1,000 Monte Carlo simulations of a hypothetical population of 10,000 patients were generated and used to determine cost-effectiveness metrics and their uncertainty.
Results: ASD surgery was cost-effective at a $150,000/QALY willingness-to-pay (WTP) threshold for younger groups with moderate disability (ICER=$91,340/QALY) favored in 60.1% of patients and high disability (ICER=$66,090/QALY) favored in 69.9% of patients. For older patients with high disability (ICER=$154,300/QALY), surgery was favored in 49.7% of patients. For all other groups, the ICER was above $194,000 and surgery was favored in less than 46.3% of patients. Younger patients gained higher incremental QALYs across all disability levels, and operative strategy demonstrated higher cost-utility in younger patients at the same baseline disability. One-way deterministic sensitivity analysis revealed that probability of failed non-operative treatment favored surgery especially in patients with low baseline disability, while probability of complicated operative course favored non-operative treatment especially in older patients.
Conclusion : Our analysis revealed that younger patients and those with higher baseline disability are more likely to achieve cost-effective surgical intervention. These findings set a basis for further investigation that could better inform clinical decision-making for elderly patients experiencing ASD.
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