Assessing the prognostic impact of body composition phenotypes on surgical outcomes and survival in patients with spinal metastasis: a deep learning approach to preoperative CT analysis

OBJECTIVE The prognostic significance of body composition phenotypes for survival in patients undergoing surgical intervention for spinal metastases has not yet been elucidated. This study aimed to elucidate the impact of body composition phenotypes on surgical outcomes and 5-year survival. METHODS The records of patients treated surgically for spinal metastases between 2010 and 2020 were retrospectively evaluated. A deep learning pipeline assessed preoperative CT scans obtained within 3 months of surgery and identified muscle and fat content and composition. These data were used to categorize patients into 4 body composition phenotypic groups: 1) not sarcopenic, not obese; 2) sarcopenia alone; 3) obesity alone; and 4) sarcopenic obesity (SO). The groups were matched using a comprehensive propensity-matching procedure. Rates of postoperative outcomes and survival were evaluated. Cox proportional hazard models were used to evaluate the influence of body composition phenotypes on 5-year survival. Kaplan-Meier plots were used to evaluate survival probability further. RESULTS Following a propensity-matching procedure, 102 matched patient records were identified (not sarcopenic, not obese, n = 24; sarcopenia alone, n = 27; obesity alone, n = 37; and SO, n = 14). SO was found to be associated with a significantly increased mortality risk within 60 months (HR 3.27, 95% CI 1.43–7.48). Kaplan-Meier plots demonstrate evident divergence in survival probability within 5 years among patients in the SO group compared to the others (log-rank test, p = 0.022). Additionally, time to death was also lower in patients with SO (p = 0.018). Significant differences in postoperative ambulation rates were noted among patients with SO (p = 0.048), whereas no preoperative difference existed (p = 0.12). No significant differences in postoperative disposition, length of hospital stay, wound-related complications, or inpatient medical complications were otherwise noted (p > 0.05). CONCLUSIONS This study identifies SO as a distinct prognostic factor for increased mortality risk in patients undergoing surgery for spinal metastases, highlighting the complex interplay between body composition and patient outcomes. These findings advocate for integrating body composition analysis into preoperative assessment and tailored postoperative care strategies, promoting personalized treatment plans to improve survival and quality of life for this vulnerable patient population.