Does Low-Grade Versus High-Grade Bilsky Score Influence Local Recurrence and Overall Survival in Metastatic Spine Tumor Surgery?

Abstract

Background and objectives: Spinal cord compression caused by spinal tumors is measured using the epidural spinal cord compression scale, also known as the Bilsky score. Whether Bilsky score predicts short-/long-term outcomes remains unknown. The objectives were to determine the correlation of Bilsky score 0-1 vs 2-3 with regards to (1) preoperative presentation, (2) perioperative variables, and (3) long-term outcomes.

Methods: A single-center, retrospective evaluation of a cohort of patients undergoing metastatic spine surgery was performed between 01/2010 and 01/2021. Multivariable logistic/linear/Cox regression were performed controlling for age, body mass index, race, total decompressed levels, tumor size, other organ metastases, and postoperative radiotherapy/chemotherapy.

Results: Of 343 patients with extradural spinal metastasis, 92 (26.8%) were Bilsky 0-1 and 251 (73.2%) were Bilsky 2-3. Preoperatively, patients with Bilsky 2-3 lesions were older ( P = .008), presented more with sensory deficits ( P = .029), and had worse preoperative Karnofsky Performance Scale (KPS) ( P = .002). Perioperatively, Bilsky 2-3 patients had more decompressed levels ( P = .005) and transpedicular decompression ( P < .001), with similar operative time ( P = .071) and blood loss ( P = .502). Although not statistically significant, patients with Bilsky 2-3 had more intraoperative neuromonitoring changes ( P = .412). Although rates of complications ( P = .442) and neurological deficit ( P = .852) were similar between groups, patients with Bilsky 2-3 lesions had a longer length of stay ( P = .007) and were discharged home less frequently ( P < .001). No difference was found in 90-day readmissions ( P = .607) and reoperation ( P = .510) Long-term: LR ( P =.100) and time to LR (log-rank; P =0.532) were not significantly different between Bilsky 0-1 and Bilsky 2-3 lesions. However, patients with Bilsky 2-3 lesions had worse postoperative KPS ( P < .001), worse modified McCormick scale score ( P = .003), shorter overall survival (OS) (log-rank; P < .001), and worse survival at 1 year ( P = .012). Bilsky 2-3 lesions were associated with shorter OS on multivariable Cox regression (hazard ratio = 1.78, 95% CI = 1.27-2.49, P < .001), with no significant impact on time to LR (hazard ratio = 0.73, 95% CI = 0.37-1.44, P = .359).

Conclusion: Bilsky 2-3 lesions were associated with longer length of stay, more nonhome discharge, worse postoperative KPS/modified McCormick scale score, shorter OS, and reduced survival at 1 year. Higher-grade Bilsky score lesions appear to be at a higher risk for worse outcomes. Efforts should be made to identify metastatic spine patients before they reach the point of severe spinal cord compression..