Impact of Preoperative Nutritional Status on Morbidity and Mortality in Elderly Patients Undergoing Spine Surgery for Metastatic Spinal Tumors: Utility of the Geriatric Nutritional Risk Index

Introduction: Malnutrition is associated with poor surgical outcomes in the elderly, but its impact on spine surgery for metastatic spinal tumors is not well understood. This study aims to evaluate the associations between preoperative nutritional status, as measured by Geriatric Nutritional Risk Index (GNRI), and postoperative morbidity and mortality in elderly patients undergoing spine surgery for metastatic spinal tumors.

Methods: A retrospective cohort study was performed using the 2011-2022 ACS NSQIP database. All elderly patients (≥ 65 years old) were categorized by GNRI score: Normal, Malnourished, and Severely Malnourished. Using receiver operating characteristic (ROC) and multivariable analyses, we compared the discriminative thresholds and independent associations of GNRI, the modified 5-item frailty index (mFI-5), and greater patient age with any adverse event, extended hospital length of stay (LOS), non-routine discharge, and 30-day mortality.

Results: Of the 659 patients identified, 277 (42.0%) had Normal nutritional status, 163 (24.7%) were Malnourished, and 219 (33.2%) were Severely Malnourished. The Severely Malnourished cohort had significantly increased proportions of electrolyte abnormalities (p=0.019) and anemia (p < 0.001), with a significant decrease in BMI and albumin levels across cohorts (p < 0.001). Malnourished and Severely Malnourished patients had significantly longer LOS (Normal: 8.6 ± 7.1 days vs. Malnourished: 9.1 ± 6.2 days vs. Severely Malnourished: 12.5 ± 8.6 days, p< 0.001) and non-routine discharge (Normal: 39.7% vs. Malnourished: 57.9% vs. Severely Malnourished: 66.7%, p< 0.001). The Severely Malnourished cohort had significantly increased 30-day mortality (Normal: 6.5% vs. Malnourished: 13.5% vs. Severely Malnourished: 17.4%, p=0.001). On multivariate analysis, Severely Malnourished status was independently associated with any AE [aOR: 1.59; p=0.036], extended LOS [aOR: 2.17; p=0.001], non-routine discharge [aOR: 1.99; p=0.001], and 30-day mortality [aOR: 2.28; p=0.013]. Malnourished status was independently associated with non-routine discharge [aOR: 1.84; p=0.005].

Conclusion : Our study suggests that preoperative GNRI-defined malnutrition is associated with a higher risk of adverse postoperative outcomes in elderly patients undergoing spine surgery for metastatic spinal tumors.