Visceral Fat Volume From Standard Preoperative CT is an Independent Predictor of Short-term Survival in Patients Undergoing Surgery for Metastatic Spine Disease.

Abstract

This is a retrospective cohort. Determine the relationship of body morphometry to postoperative survival in patients with vertebral metastases. Most operations for vertebral metastases aim for palliation not cure, yet expected patient survival heavily influences treatment plans. We seek to demonstrate that preoperative fat and muscle volumes on standard-of-care computed tomography (CT) are independent predictors of survival after surgery for vertebral metastases. Included data were preoperative neurological status, adjuvant treatments, CT-assessed body composition, health comorbidities, details of oncologic disease, and Tomita and Tokuhashi scores. Body composition-visceral fat area, subcutaneous fat area, and total muscle area-were assessed on preoperative L3/4 CT slice with Image J software. Multivariable logistic regressions were used to determine independent predictors of 3-, 6-, and 12-month survival. We included 75 patients (median age, 57, 57.3% male, 66.7% white) with the most common primary lesions being lung (17.3%), prostate (14.7%), colorectal (12.0%), breast (10.7%), and kidney (9.3%). The only independent predictor of 3-month survival was visceral fat area [95% confidence interval (CI): 1.02-1.23 per 1000 mm; P=0.02]. Independent predictors of survival at 6 months were body mass index (95% CI: 1.04-1.35 per kg/m; P=0.009), Karnofsky performance status (95% CI: 1.00-1.15; P<0.05), modified Charlson Comorbidity Index (95% CI: 1.11-7.91; P=0.03), and postoperative chemotherapy use (95% CI: 1.13-4.71; P=0.02). Independent predictors of 12-month survival were kidney primary pathology (95% CI: 0.00-0.00; P<0.01), body mass index (95% CI: 1.03-1.39 per kg/m; P=0.02), and being ambulatory preoperatively (95% CI: 1.28-17.06; P=0.02). Visceral fat mass was an independent, positive predictor of short-term postoperative survival in patients treated for vertebral metastases. As a result, we believe that the prognostic accuracy of current predictors may be improved by the addition of visceral fat volume as a risk factor.