Changes in skeletal muscle mass index and fat mass index during rehabilitation for traumatic brain injury and stroke measured by bioelectrical impedance analysis

Although malnutrition may negatively impact the outcomes of rehabilitation and increase the cost of care, there are still no valid nutritional assessment methods appropriate for specific groups of patients undergoing rehabilitation. This study aimed to determine if a multifrequency bioelectrical impedance is suitable for monitoring the changes in body composition of brain-injured patients for whom individualized nutritional goals were set during rehabilitation. Fat mass index (FMI) and skeletal muscle mass index (SMMI) were examined by Seca mBCA515 or portable Seca mBCA525 device within 48 h of admission and before discharge in 11 traumatic brain injury (TBI) and 11 stroke patients with admission Nutritional Risk Screening 2002 scores ≥2. The changes in outcomes and plausible interactions were examined between the admission values and the values estimated for the 18th day (minimum length of stay in the sample) using a repeated measure mixed-sample analysis of covariance. In patients with low FMI at admission (mainly younger, TBI patients, with longer ICU stay), there was no change over time whereas, in those with high admission FMI (older, stroke patients, with shorter ICU stay), a decrease was observed (significant interaction F(1,19) = 9.224 P = 0.007 Part. η² = 0.327). The SMMI significantly increased over time (F(1,19) = 5.202 P = 0.034 Part. η² = 0.215) independently of gender, age, days spent in ICU and cause of brain injury. Our results suggest that bioelectrical impedance analysis is feasible and informative for monitoring the changes in body composition during rehabilitation, which also requires consideration of demographic and pre-rehabilitation characteristics.