Should Proximal Fixation Be at C2 or C3-C4? An Application of the Operative Value Index for Elective Posterior Cervical Decompression and Fusion.

Abstract

Introduction: There is clinical equipoise regarding the ideal upper instrumented vertebrae (UIV) for elective posterior cervical decompression and fusion (PCDF). Instrumentation may be performed at the axial C2 level, or at the subaxial C3/C4 vertebrae. To our knowledge, a true "value" (outcomes per dollar spent) comparison axial versus subaxial UIV for PCDF has never been performed.

Methods: We retrospectively identified 275 long-segment (≥ 3-levels fused) PCDFs with available Neck Disability Index (NDI) scores at baseline and at 3-months postoperatively. C2 UIV (n=67) was compared to C3/C4 UIV(n=208). Time-driven activity-based costing (TDABC) was applied to identify the true intraoperative costs for each case. The Operative Value Index (OVI) was defined as the percent improvement in NDI score from baseline, per $1,000 spent intraoperatively. Multivariable regression analysis was performed to compare intraoperative costs and OVI between C2 and C3/C4 UIV.

Results: The average total cost of a C2 construct was $13,751 ($5,247), compared to $10,778 ($2,237) for C3/C4 (p<0.001). 40% of C2 cases and 32% of C3/C4 cases, respectively, achieved clinically significant improvement in NDI. On multivariable regression analysis, C2 UIV was associated with significantly higher total cost (beta-coefficient: $1,814 +/- 553, p=0.001), supply cost (beta-coefficient: $1,185 +/- $482, p=0.015) and personnel cost (beta-coefficient: $275 +/- $116, p=0.019). However, there was no significant difference in OVI (p=0.155) between C2 and C3/C4 UIV.

Conclusions: Although the C2 UIV construct incurred significantly higher intraoperative costs compared to C3/C4 UIV, there was no significant difference in "value" between axial and subaxial UIV.