Qualitative muscle mass index as a predictor of skeletal muscle function deficit in Asian older adults

Abstract

Aim: The present cross-sectional study was carried out among community-dwelling Koreans to determine the validity of various muscle mass indices and to propose more clinically relevant diagnostic criteria.

Methods: This study measured the anthropometrics, body composition and physical capability of 415 older Koreans. Skeletal muscle indices were calculated by dividing appendicular lean mass by height or weight. Apart from this, we adjusted appendicular lean mass for body mass index, body surface area or waist-to-height ratio, which we then named the qualitative muscle mass index. Skeletal muscle function deficit was defined as a combination of weakness and slowness.

Results: Qualitative muscle indices were closely associated with physical capabilities. Receiver operating characteristic and logistic analyses showed that qualitative muscle indices had significantly greater discriminatory powers regarding low muscle function than did the height-adjusted index in both men and women, and even showed higher discriminatory potentials than the weight-adjusted index in men (all P < 0.05). The cut-off values of qualitative muscle indices of body mass index-, body surface area-, and waist-to-height ratio-adjusted indices for identifying functional deficits were 0.760, 11.40 and 34.18 for men, and 0.530, 8.91 and 23.07 for women, respectively.

Conclusions: The present study suggests that qualitative muscle indices are more accurate in predicting low muscle function than are height- and weight-adjusted indices, because they consider anthropometric characteristics as part of the definition. The results might provide new avenues for conceptualizations of sarcopenia accompanied by obesity, and can be used as ethnic-specific reference values of muscle mass indices based on functional outcome in an elderly Korean/Asian population. Geriatr Gerontol Int 2017; 17: 99-107.

Keywords: anthropometry; body mass index; elderly; sarcopenia; skeletal muscle.