Sarcopenia: The need to establish different cutoff points of fat-free mass for the Chilean population

•Appendicular fat-free mass was calculated from 4062 dual-energy x-ray absorptiometries, and four possible cutoff points for sarcopenia were obtained.•The appendicular fat-free mass of young Chileans is lower than that from Western countries but similar to Latin American data; therefore, establishin...

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Published in:	Nutrition (Burbank, Los Angeles County, Calif.) Vol. 57; pp. 217 - 224
Main Authors:	Wigodski, Sabrina, Carrasco, Fernando, Bunout, Daniel, Barrera, Gladys, Hirsch, Sandra, de la Maza, Maria Pia
Format:	Journal Article
Language:	English
Published:	United States Elsevier Inc 01-01-2019 Elsevier Limited
Subjects:	Absorptiometry, Photon Adolescent Adult Adults Age Age Factors Aged Aged, 80 and over Appendicular fat-free mass Appendicular fat-free mass index Body Composition Body Fluid Compartments Body mass Body mass index Body Weight DEXA Diagnostic systems Dual energy X-ray absorptiometry dynamometry Expected values Fat-free body mass Female Food science Hand Strength Handgrip strength Humans Magnetic resonance imaging Male Mathematical analysis Men Methods Middle Aged Muscle function Muscle, Skeletal - metabolism Muscle, Skeletal - physiology Muscles Musculoskeletal system Nutrition Obesity Older people Population Reference Values Regression analysis Sarcopenia Sarcopenia - diagnosis Sarcopenia - metabolism Sex Factors Sexes Skeletal muscle Software Stratification Strength Women Young Adult Young adults Sarcopenia Appendicular fat-free mass Handgrip strength DEXA Appendicular fat-free mass index dynamometry
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Summary:	•Appendicular fat-free mass was calculated from 4062 dual-energy x-ray absorptiometries, and four possible cutoff points for sarcopenia were obtained.•The appendicular fat-free mass of young Chileans is lower than that from Western countries but similar to Latin American data; therefore, establishing sarcopenia as 2 standard deviation below average would not be appropriate and –1 standard deviation could be more suitable but gives cutoffs even higher than Baumgartner's.•Only by calculating the percentage of muscle mass in relation to total mass, the expected age-related increase in frequency of sarcopenia was observed, and correlated with handgrip strength in elderly women. International cutoff points for the diagnosis of sarcopenia are not applicable to the Chilean population due to previous evidence of a lower lean mass and strength in this population. Dual-energy x-ray absorptiometry is used to establish fat-free mass cutoff points to define sarcopenia in the Chilean population and analyze its association with handgrip strength in older adults. Appendicular fat-free mass (AFFM) was calculated from 4062 dual-energy x-ray absorptiometries of healthy Chileans, ages 18 to 99 y. Possible cutoff points for sarcopenia were obtained using four methods: A) Normative, –2 standard deviation (SD) below mean AFFM/height2 (AFFMI) of adults age <40 y; B) normative –1 SD, –1 SD under the average AFFMI of adults age <40 y; C) stratification, 25th percentile of the residual distribution obtained with the regression equation to predict AFFM in the entire sample; and D) percentage, –2 SD under the average skeletal muscle mass/total body mass of individuals age <40 y. Additionally, in a subsample of elderly subjects, the correlation between handgrip strength and the four calculated cutoff points was analyzed. Using the normative method, sarcopenia was defined as an AFFMI <6.4 kg/m2 in men and <4.8 kg/m2 in women and at –1 SD, the cutoff points were <7.5 kg/m2 and <5.6 kg/m2, respectively. With the stratification method, sarcopenia was defined as –1.33 kg and –1.05 kg of AFFM with respect to the expected value according to the regression equation in men and women, respectively. According to the percentage method, the cutoff points for sarcopenia were <30% and <22.9% in men and women, respectively. The concordance of the four methods was slight to moderate. Only the percentage method showed a progressive increase in the proportion of subjects with sarcopenia as age increased. The latter and the normative –1 DS predicted lower handgrip strength in elderly women, unlike the other diagnostic methods. For elderly men, only the normative –1 DS method predicted weaker handgrip strength. The AFFM of young Chileans is lower than that reported in Western countries but similar to Latin American data; therefore, the use of the traditional normative method would not be appropriate with –2 SD to establish cutoff points, and using –1 DS resulted in values that are higher than Baumgartner's. Stratification is advantageous because this method throws expected values of AFFM for each population; however, overdiagnosis of sarcopenia is a possibility and thus the method requires a representative sample. The percentage method is simple and showed the expected decrease of muscle mass with age, and also correlated well with handgrip strength in elderly women. Thus, this method represented our method of choice to detect sarcopenia.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0899-9007 1873-1244
DOI:	10.1016/j.nut.2018.05.031