What is the Value Proposition of Evidence-Based Guidelines? An Application of the Operative Value Index for Lumbar Fusions

Abstract

Elective lumbar fusions have received criticism for inappropriate utilization. Here, we use a novel Operative Value Index (OVI) to assess whether "indicated", evidence-based lumbar fusions are associated with increased value (outcomes per dollar spent). This study is a retrospective analysis of a prospective observational cohort of 294 patients undergoing elective lumbar fusions at a single large academic institution. All patients were preoperatively evaluated by a panel of neurosurgeons for concordance with evidence-based medicine (EBM), determined through guidelines from the North American Spine Society. Oswestry Disability Index (ODI) scores were collected for all patients both preoperatively and at 6-months postoperatively. Time-driven activity-based costing (TDABC) was employed to determine both direct and indirect intraoperative costs. The OVI was defined as the percent improvement in ODI per $1,000 spent intraoperatively. Generalized linear mixed model (GLMM) regression, adjusting for confounders, was performed to assess whether EBM-concordant surgeries were associated with higher OVI. Of 294 elective lumbar fusions, 92.9% (n=273) were EBM-concordant. The average total cost of an EBM-concordant lumbar fusion was $17,932 (supplies: $13,020; personnel: $4,314), compared to $20,616 (supplies: $15,467; personnel: $4,758) for an EBM-discordant fusion. Average OVI was 2.27 for a concordant fusion, compared to 0.11 for a discordant fusion. GLMM analysis revealed that EBM-concordant cases were associated with significantly higher OVI (β-coefficient 2.0, p<0.001). EBM-concordant fusions were associated with 2% greater improvement in ODI scores from baseline for every $1,000 spent intraoperatively. Systematic methods for increasing guideline adherence for lumbar fusions could therefore improve value at scale.