Sarcopenia Independently and Accurately Predicts Survival in Patients Undergoing Spine Surgery for Metastatic Tumors: A Multicenter Retrospective Cohort Study

BACKGROUND CONTEXT: Predicting survival and surgical morbidity in patients with spinal metastases would help guide clinical decision making and stratify treatments between surgical intervention and palliative care. PURPOSE: To evaluate whether the frailty/sarcopenia paradigm, as measured by psoas size, is strong predictor of survival in patients undergoing surgery for spinal metastasis. To directly compare psoas size with current standards of predicting survival for surgery for spinal metastasis, including Tokuhashi score, Tomita score, and Karnofsky Performance Status (KPS). STUDY DESIGN/SETTING: Multi-center retrospective cohort. PATIENT SAMPLE: Patients from four academic tertiary care centers who had undergone surgery for spinal metastasis. OUTCOME MEASURES: Overall mortality. METHODS: Morphometric measurements were taken of the psoas muscle at the L4 vertebral level \u3c200 days from surgery. Mortality hazard ratios were calculated using multivariate analysis, with variables included from past medical history, type and extent of tumor spread, type and intensity of surgery, and postoperative chemotherapy or radiation. RESULTS: A total of 271 patients from four institutes were identified. Psoas size was predictive of overall mortality; patients in the smallest psoas tertile had shorter overall survival compared to the middle (OR 0.52, p\u3c0.001) and largest tertile (OR 0.45, p\u3c0.001). Psoas size predicted overall mortality more strongly than Tokuhashi score (OR 0.91, p=0.010), Tomita score (OR 1.07, p=0.04), and KPS (OR 0.99, p=0.58). Psoas size was also predictive of 90-day survival; patients in the smallest psoas tertile had shorter 90-day survival compared to the middle (OR 0.24, p=0.003) and largest tertile (OR 0.16, p=0.001). Psoas size predicted 90-day mortality more strongly than Tokuhashi score (OR 0.73, p=0.002), Tomita score (OR 1.00, p=0.92), and KPS (OR 0.98, p=0.39). CONCLUSIONS: In patients undergoing surgery for spine metastases, psoas size as a surrogate for frailty/sarcopenia predicts 90-day and overall mortality, independent of demographical, functional, oncological and surgical characteristics. The sarcopenia/frailty paradigm is a stronger predictor of survival at these time points than the Tokuhashi score, Tomita score and KPS. Psoas size can be used in clinical decision-making to select which patients with metastatic spine tumors are appropriate surgical candidates. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs