The significance of body mass index in calculating the cut-off points for low muscle mass in the elderly: methodological issues.

Roma Krzymińska-Siemaszko,Aleksandra Suwalska,Katarzyna Wieczorowska-Tobis,Beata Madej-Dziechciarow,Natasza Czepulis,Anna Fryzowicz,Lechoslaw B Dworak

doi:10.1155/2014/450396

Abstract

Objectives. Cut-off points (COPs) for appendicular lean mass (ALM) index, essential to define low muscle mass (LMM) in the elderly, have never been officially defined for Poland. The aim of the study was to establish them. Additionally, the significance of body mass index (BMI) for correctly defining the COPs in a young, healthy reference group was assessed. Methods. The study was composed of reference group (n = 1113) and the elderly group (n = 200). In all subjects, body composition was assessed by bioimpedance analysis, and ALM index was calculated. Next, COPs (kg/m2) were set up for the whole reference group and for particular subgroups with different BMIs separately. They were used to diagnose sarcopenia in the elderly. Results. COP for all young females was 5.37 (COP-F), while it was equal to 5.52 (COP-F2) when only those with a recommended BMI (18.50–24.99 kg/m2) were taken into consideration. For males, it was 7.32 and 7.29, respectively. Only 7% of elderly females had LMM based on COP-F and 15% had LMM based on COP-F2 (P < 0.05); for males, the percentages were 18% and 16%, respectively. Conclusions. COPs for LMM for Poland are 5.52 kg/m2 (females) and 7.29 kg/m2 (males). The reference group BMI is an important factor in establishing COPs for low muscle mass.

Highlights

Over 25 years ago, in 1988, Irving Rosenberg stated that “no decline with age is more dramatic or potentially more functionally significant than the decline in muscle mass.” He suggested “that to provide recognition by the scientific community this phenomenon needed a name” [1]
The mean appendicular lean mass (ALM) index for all females in the reference group was 6.55 ± 0.59 kg/m2 and the cutoff point for low muscle mass was equal to 5.37 kg/m2
The mean ALM index values changed with body mass index (BMI), and the differences were statistically significant (r = 0.675, P < 0.001)

Summary

Introduction

Over 25 years ago, in 1988, Irving Rosenberg stated that “no decline with age is more dramatic or potentially more functionally significant than the decline in muscle mass.” He suggested “that to provide recognition by the scientific community this phenomenon needed a name” [1]. Over 25 years ago, in 1988, Irving Rosenberg stated that “no decline with age is more dramatic or potentially more functionally significant than the decline in muscle mass.”. He suggested “that to provide recognition by the scientific community this phenomenon needed a name” [1]. Sarcopenia was redefined as age-related, generalised, and progressive loss of both skeletal muscles mass and their strength [5]. This has been reflected in four different diagnostic algorithms proposed over the last few years

Objectives

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Conclusion