142 An Economic Analysis of the Cervical Spondylotic Myelopathy Surgical (CSM-S) Trial: Cost-Effectiveness of Anterior and Posterior Approaches

INTRODUCTION: Surgery for cervical spondylotic myelopathy (CSM) improves quality of life but surgical approaches might differ by cost. METHODS: We conducted a post-hoc cost-effectiveness analysis of a prospective randomized trial comparing surgical approaches for CSM. Patients 40 to 85 years of age with CSM were enrolled across 15 sites in North America and randomized (2:3) to either anterior surgery (ACDF) or posterior surgery (LP or PCDF, at surgeon’s discretion). A cost analysis was performed from a societal perspective with a one-year time horizon, including only patients from the United States. Direct costs were estimated using 2022 Medicare reimbursement rates for professional fees and cost-to-charge ratios. Indirect costs were estimated using a human capital approach based on patient surveys. Effectiveness was measured in quality-adjusted life-years (QALYs) using the Euro-Qol-5-Dimensions (EQ-5D) at one year. RESULTS: 153 patients were included as-treated in a three-way cost analysis by surgical approach. Index hospitalization costs were higher after PCDF than ACDF and LP ($32,507 vs. $24,991 vs. $24,574, p<0.0001). 34 patients (22.2%) had complications. Complication costs and lost wages did not differ between groups. One-year total costs were higher after PCDF than ACDF and LP ($49,590 vs. $39,678 vs. $40,716; p=0.0072). For 71 patients with one-year costs and EQ-5D outcomes available, PCDF was associated with lower QALY gains than ACDF (0.687 vs. 0.786, p=0.029) and LP (0.687 vs. 0.791, p=0.062). CONCLUSIONS: Among patients enrolled in the CSM-S Trial, LP and ACDF had similar cost-utility. PCDF was less cost-effective, yielding worse outcomes with higher costs, driven primarily by index hospitalization.