Determining the optimal body weight for individuals with severe motor and intellectual disabilities (SMID) lacks a standardized approach. In this study, we aimed to develop a formula to estimate the ideal body weight for each SMID patient, considering factors such as reduced muscle and bone mass. We analyzed data from 111 SMID patients (56 male, 55 female; age range 20 to 73 y) who underwent blood tests measuring creatinine (Cr) and cystatin C (cysC) for clinical reasons between Feb. 2018 and Feb. 2023. To create the optimal body weight formula, we utilized three variables: height, estimated glomerular filtration (eGFR)-Cr, and eGFR-cysC. The validity of the formula was assessed by comparing the measured triceps subcutaneous fat thickness (TSF) to the reference TSF (%TSF), evaluating how accurately it reflects the appropriate physique. The derived optimal body weight formula is as follows: Optimal body weight=(height)2×(18.5-25.0)×{1-0.41×(1-eGFR-cysC/eGFR-Cr)}×0.93. Our formula demonstrated validity when using %TSF as an indicator. Establishing a method to determine optimal body weight in SMID patients, considering their low muscle and bone mass, is crucial for accurate nutritional assessment and subsequent nutritional management.
Keywords: bone mass; creatinine; cystatin C; muscle mass; optimal body weight; severe motor and intellectual disabilities.