Frailty as a Predictor of Outcomes After Fibula Free Flap for Head and Neck Reconstruction: A Multi‐Institutional Analysis Using the mFI ‐5

BACKGROUND: Chronological age inadequately reflects physiologic vulnerability in older adults undergoing complex reconstruction. Frailty, quantified by the 5-item Modified Frailty Index (mFI-5), may better stratify perioperative risk in fibula free flap (FFF) reconstruction for head and neck defects, but its impact remains underdefined. METHODS: A retrospective cohort study of 406 adults undergoing FFF reconstruction (ACS-NSQIP, 2009-2023) evaluated the association between mFI-5 and 30-day postoperative outcomes. Multivariable logistic regression identified independent predictors of medical and surgical complications. RESULTS: Higher mFI-5 scores were associated with increased medical complications (14.1% mFI-5 = 0 vs. 34.3% mFI-5 = 2; p = 0.02), including pneumonia and myocardial infarction. mFI-5 = 1 (aOR 1.84; 95% CI, 1.01-3.47) and mFI-5 = 2 (aOR 3.45; 95% CI, 1.38-8.57) independently predicted medical complications; mFI-5 = 2 also predicted surgical complications (aOR 2.27; 95% CI, 1.00-5.43). CONCLUSIONS: Frailty is a stronger predictor of postoperative morbidity than chronological age. Incorporating frailty assessment may enhance risk stratification and perioperative decision-making.