Are Mildly Disabled Patients Appropriate for Spine Bundles? An Application of the Operative Value Index.

Introduction: Many studies have evaluated the effect of preoperative disability status on functional outcomes following spine surgery. However, no research has compared the "value" (outcomes per dollar spent) of surgery for patients with different levels of diagnosis-specific disability.

Methods: We retrospectively reviewed 429 patients who underwent neurosurgical anterior cervical discectomy and fusion. Time-driven activity-based costing (TDABC) was used to calculate total intraoperative costs. Neck Disability Index (NDI) scores were recorded at baseline and three months post-surgery. Patients were categorized into groups based on their preoperative NDI score. Our primary outcome was a novel Operative Value Index (OVI), defined as the percent change in NDI per $1,000 spent intraoperatively. Generalized linear mixed model regression was used to determine if severe-to-complete ("high") baseline neck disability was significantly associated with OVI and total cost.

Results: Compared to patients with "high" preoperative neck disability, the OVI was significantly lower for patients with no neck disability (β-coefficient: -14.0, p<0.001) and mild neck disability (β-coefficient: -4.06, p<0.001). There were no significant associations between the NDI groups and total intraoperative cost.

Conclusion: Surgery provided the most value for patients with "high" baseline neck disability, with more favorable outcomes per dollar spent compared to those with low baseline neck disability. Patients with low baseline neck disability may therefore suboptimal candidates for bundled payments, emphasizing the importance of careful patient selection to optimize resource use and outcomes in value-based care models.