Functional nutritional frailty predicts complications after microvascular free flap reconstruction

Outcomes after microvascular free flap reconstruction depend not only on surgical technique but also on patient-related factors such as nutritional and functional reserve. However, conventional biochemical markers may not fully reflect the patient's physiological reserve. This study aimed to evaluate whether functional nutritional screening tools can predict free flap-related complications.

Eighty patients who underwent microvascular free flap reconstruction were retrospectively analyzed. Preoperative nutritional status was assessed using the Mini Nutritional Assessment (MNA) and SARC-F questionnaire. Patients were categorized as high risk (HR) or low risk (LR) according to these screening tools. Free flap-related complications within 30 days were compared between groups. Multivariable logistic regression analysis was performed as an exploratory analysis to evaluate the association between functional nutritional frailty and flap-related complications.

Twenty-nine patients (36.3%) were classified as high risk. Flap-related complications, defined as a composite outcome including total flap loss, partial flap necrosis, vascular thrombosis requiring re-exploration, surgical site infection, and wound dehiscence, occurred in 17 patients (21.3%). Complication rates were significantly higher in the HR group compared with the LR group (55.2% vs. 1.9%, p < 0.001), corresponding to an approximately 29-fold increase in risk. In multivariable analysis, functional nutritional frailty remained associated with postoperative complications in the exploratory multivariable model (OR 74.4, 95% CI 8.8-629.6, p < 0.001), whereas diabetes mellitus and smoking were not associated with complication development.

Functional nutritional frailty assessed by simple clinical screening tools such as MNA and SARC-F was strongly associated with flap-related complications after free flap reconstruction. Incorporating these tools into routine preoperative assessment may help identify high-risk patients and optimize perioperative management.