Predicting Postoperative Complications in Lung Cancer Spinal Metastases: A Nomogram Based on Nutritional, Low Psoas Muscle Index, and Functional Status

Objective: This study seeks to investigate the association between nutritional, muscular, and functional status and moderate-to-severe postoperative complications (Clavien–Dindo ≥ grade II) in patients with lung cancer spinal metastases and to construct an individualized risk prediction nomogram. Methods: A total of 162 patients with histologically confirmed lung cancer spinal metastases who underwent surgery were retrospectively enrolled. Preoperative clinical data were collected. Univariate and multivariate logistic regression analyses were used to identify independent risk factors for postoperative complications, with variable selection based on a combination of statistical significance and clinical judgment. A nomogram model was constructed and evaluated using receiver operating characteristic curve, calibration curve, and decision curve analysis. Internal validation was performed using the bootstrap method. For exploratory assessment of the model’s clinical stratification capability, patients were classified into low-, medium-, and high-risk groups based on tertiles of the predicted probability. Results: The incidence of Clavien–Dindo ≥ grade II complications during postoperative hospitalization or within 14 days was 57.4%. Multivariate analysis suggested that lower psoas muscle index (low PMI) (OR = 4.131, p = 0.034), lower body mass index (BMI) (continuous: OR = 0.539 per 1 kg/m2 increase, p = 0.001, indicating that lower BMI was associated with higher risk), lower prognostic nutritional index (PNI) (OR = 0.456, p < 0.001), and lower Karnofsky Performance Status (KPS) score (OR = 0.890, p = 0.009) were identified as potential independent factors associated with postoperative complications. The nomogram achieved an Area Under the Curve of 0.907, showed acceptable calibration (Hosmer–Lemeshow test, p = 0.735), and demonstrated a favorable net clinical benefit in the decision curve analysis. In the exploratory risk stratification analysis, complication rates in the low-, medium-, and high-risk groups were 28.8%, 63.6%, and 78.2%, respectively (p < 0.001). Patients with complications had significantly longer hospital stays (median 20 vs. 13 days). Conclusions: In this cohort, low PMI, low BMI, low PNI, and low KPS were identified as potential independent factors associated with short-term moderate-to-severe postoperative complications. The nomogram may preliminarily predict the risk and might serve as a quantitative reference for individualized perioperative management, but its clinical utility requires further confirmation in external validation. The exploratory risk stratification suggests that the model has preliminary potential for clinical discrimination.