Can the Malnutrition Universal Screening Tool (MUST) Predict Healing Complications Following Microvascular Reconstruction of the Head and Neck?

Study design: Retrospective cohort study.

Objective: Malnutrition has been found to have negative effects on the immune system and inflammatory responses, impairing the wound healing process. Free flap failure is a serious complication in patients undergoing microvascular reconstruction, as it increases patient morbidity, length of stay in the hospital, patient, and hospital costs, as well as causes the need for further surgical interventions¹. Malnutrition is estimated to be present in 35-50% of head and neck cancer patients with higher rates in those experiencing hypo-oropharyngeal disease. This is often caused by functional and pain limitations from due to disease burden causing odynophagia and dysphagia. The Malnutrition Universal Screening Tool (MUST) is recommended for risk screening and provides three scores for risk classification: high, intermediate, and low². We argue that the use of MUST as a preoperative assessment tool is useful to predict postoperative surgical site infection and delayed wound healing in patients that will undergo reconstruction with free flaps for head and neck defects.

Methods: A retrospective cohort study was designed to include all subjects who underwent head and neck microvascular free tissue transfer at a single institution between 2013 and 2019. Primary and secondary reconstructions were included, for benign or malignant pathology, osteonecrosis, osteomyelitis, congenital defects, and trauma. The nutritional risk was evaluated using MUST, which analyzes body mass index, weight loss, and acute disease effect, to classify patients as low, intermediate, and high risk. We further divided the subjects into two comparison groups- low-intermediate and high risk. The primary outcome was surgical site complications and delayed wound healing. Data was analyzed as frequencies and means with standard deviations, as well as Fisher's exact test and t-test. P-values <0.05 were considered statistically significant. Analyses were done utilizing IBM SPSS Statistics Version 29.

Results: 131 subjects were included for data analysis, with 54 being considered low MUST risk, 12 intermediate risk (66 low-intermediate), and 65 were high risk. The mean BMI overall was 25.5 ±5.3, and 27.2 in the low-intermediate group, and 23.7 in the high-risk group. Eighty-two subjects experienced <5-pound weight loss in the preceding 6 months to surgery, while 17 lost between 5-10 pounds, and 23 lost 10< pounds. Cancer/osteonecrosis was the etiology for 54 (82%) subjects of the low-intermediate group, and 61 (92%) of the high-risk group (P = .089). The subjects classified in High-risk group according to the MUST score had 11% more surgical site complications (P = .120) and 13.7% more delayed wound healing and dehiscence(P = .09); only 3 subjects in the study presented total flap loss and they were all in the High-risk group. Surgical site complication, delayed wound healing rates and partial or total flap loss were not increased by any specific medical comorbidity or history such as radiation or chemotherapy.

Conclusions: In conclusion, Subjects with high MUST score had increased complications and poor wound healing, and subjects with acute disease effect that induces a phase of nil per os for > 5 day have higher risk of total flap loss and surgical site complication.