Abstract

Background: Post-operative infection hampers recovery in older adults after spinal surgery. We analyzed infection patterns and risk factors for deep/organ-space infection.

Methods: A retrospective review of 317 patients ≥ 65 years (January 2019–October 2024) identified superficial versus deep/organ-space infections. Baseline, laboratory and operative variables were compared; independent predictors were determined with multivariable logistic regression. Model performance was gauged with the area under the receiver-operating-characteristic curve (AUC) and calibration tests.

Results: Superficial infection occurred in 200 patients (63.1%) and deep/organ-space infection in 117 (36.9%). Compared with superficial cases, deep infectionswere linked to greater age, higher body-mass index (BMI), diabetes, frailty, hypoalbuminemia, longer operative time and procedures involving ≥ 3 spinal levels. Multivariable analysis confirmed age, BMI, diabetes, frailty, albumin < 35 g/L, operative time, ≥ 3 levels, and intra-operative transfusion as independent predictors. The model demonstrated good discrimination (AUC = 0.82) and acceptable calibration. Deep/organ space infection was associated with longer hospitalization (16.7 ± 5.9 vs. 12.3 ± 4.1 days, p < 0.001), higher re-operation rates (16.2% vs. 3.5%, p < 0.001), and greater ICU utilization (18.8% vs. 7.0%, p = 0.002). Infection related mortality remained low overall (4.3%).

Conclusion: Advanced age, metabolic comorbidity, frailty and complex, prolonged surgery independently predicts deep/organ-space infection after spinal procedures in older adults. Early identification of these factors can guide targeted prevention and improve outcomes.