Skeletal Muscle Mass Index cut-offs by bioelectrical impedance analysis to determine Sarcopenia Based on healthy young or old Populations: A Comparative Study

Skeletal muscle mass index (SMMI) is a component in sarcopenia. There is no universal cut-off point and therefore each population should have its own reference values. This study aimed comparing SMMI cut-off points derived from a young population with those obtained directly from an elderly population. 237 older adult community-dwelling older than 60 years were evaluated. The skeletal muscle mass (SMM) was evaluated by bioelectrical impedance analysis (BIA). SMMI was calculated as SMM/height squared. The young population consisted of 255 participants from the same locality. The cut-off points from older person for moderate low muscle mass were 6.70 (women) and 9.20 kg/m2 (men). In this case, they were higher than those estimated from the young population (6.42 and 8.40 kg/m2for women and men). A similar trend was obtained when the cut-off points were set below the 20th percentile. When two standard deviations were used to determine the cut-off points, the values for older women were lower (5.90 kg/m2) than those obtained from young adults. There were no differences in the case of men. SMMI reference values from elderly persons is an option to diagnose sarcopenia, however prospective studies are necessary to stablish the capacity to predict functional outcomes.