Abstract: PURPOSE: To explore the relationship between the modified frailty index(mFI) and adverse outcomes after general anesthesia in elderly patients with maxillofacial space infection, so as to provide a reference for clinical risk assessment. METHODS: The clinical data of 83 elderly patients with maxillofacial space infection who required general anesthesia surgery in Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine from June 2016 to January 2025 were retrospectively analyzed. The 11-item mFI was used to assess the patients' frailty status, and they were divided into the frail group(mFI≥0.27, 43 cases) and the non-frail group(mFI<0.27, 40 cases). Univariate and multivariate logistic regression analyses were used to analyze the correlation between mFI and postoperative complications as well as length of stay(LOS). The receiver operator characteristic(ROC) curve was drawn to evaluate the predictive efficacy of mFI for prolonged LOS. RESULTS: The incidences of new-onset pneumonia (41.86% vs 20.00%), respiratory failure (19.05% vs 2.56%) and cardiovascular events (48.84% vs 23.08%) in the frail group were significantly higher than those in the non-frail group (P<0.05), and the LOS was longer(P<0.05). Multivariate logistic regression analysis showed that mFI ≥0.27 was an independent risk factor for prolonged LOS(OR=2.53, 95%CI: 1.02-6.31). ROC curve analysis showed that the predictive efficacy of mFI combined with APACHE-II score for prolonged LOS reached above the moderate level(AUC=0.772, 95%CI: 0.664-0.859). CONCLUSIONS: The modified frailty index can effectively assess the risk of adverse outcomes after general anesthesia in elderly patients with maxillofacial space infection. Its combination with APACHE-II score has high predictive value for prolonged hospital stay, which can provide a basis for perioperative diagnosis and treatment decisions.

Key words: Maxillofacial space infection, Modified frailty index, Elderly patients, Postoperative complications, Length of stay