The useful lean tissue and appendicular skeletal muscle mass indices related to physical performance in patients undergoing hemodialysis

BACKGROUND: Low muscle quantity commonly seen in patients undergoing hemodialysis (HD) is the key contributor of declined physical performance and increases the risk of morbidity and mortality. However, how to normalize muscle mass for operational criteria in this population remains unknown. OBJECTIVE: To identify the clinically useful whole body lean tissue mass (LTM) and appendicular skeletal muscle mass (ASM) indices pertinent to physical performance in patients undertaking HD. METHODS: Whole body LTM in 38 and ASM in 22 patients undergoing HD were measured by body composition monitor (BCM) and dual-energy X-ray absorptiometry (DXA), respectively. Physical performance was assessed by handgrip strength, the incremental shuttle walk test, sit-to-stand tests, gait speed, Short Physical Performance Battery and Duke Activity Status Index. Besides crude LTM and ASM, the other muscle indices were utilized normalizing for height, height squared, weight, body mass index (BMI), fat mass and body fat%. RESULTS: Regardless of BCM or DXA being used, the relationships between different muscle mass indices and physical function were not consistent. While the most useful LTM index which was strongly associated with physical function involved adjustment for height, the strongest (and most useful) ASM index was normalization for BMI. CONCLUSION: The superiority of adjustment for BMI or height (height2) recommended by international sarcopenia consensus is also suitable for patients undergoing HD. Patients’ BMI or fat mass should be considered in estimating prevalence of sarcopenia and evaluating relationship between muscle mass and physical performance.