Prognostic nutritional index versus pragmatically operationalized GLIM criteria for predicting postoperative complications and recovery in spine surgery: a prospective cohort study

Background Preoperative malnutrition increases surgical complications, yet the Prognostic Nutritional Index (PNI) and Global Leadership Initiative on Malnutrition (GLIM) criteria demonstrate conflicting validity in spine surgery populations. Methods Prospective outcome cohort with retrospectively abstracted baseline data, comprising 1,341 consecutive spine surgery patients (Chinese tertiary center, February 2022–September 2025) stratified by PNI (normal ≥45 vs. low <45) and GLIM criteria.