Métodos de estimación de la composición corporal de ancianos: análisis crítico / Body composition estimation methods in elderly: critical analysis

ABSTRACT

The objective of this study was to compare the values obtained for total body fat obtained with deuterium dilution, anthropometry and bioimpedance in 41 institutionalized elderly individuals (65-90 years old). The values obtained with each technique were compared using the graphic analysis proposed by Bland and Altman, that plots the difference between measurements with both methods against their average. In men (n=20) and women (n=21), the best degree of agreements was obtained between the values measured by deuterium dilution and those calculated from skinfolds (mean difference=1.4 percent and 6.9 percent respectively). The limits of agreement (ñ2SD) for skinfolds reached a maximun of 14.8 percent in men, and 16.8 percent in women. These values tend to underestimate fat in the obese and overestimate it in thinner subjects. For bioimpedance and deuterium dilution, the inter-method difference is significantly greater 9.3 percent in men and 14.7 percent in women. This lack of agreement is attributed to the fact that the bioimpedance equipment utilizes equations validated for younger adults. In conclusion, estimation of body composition using skinfolds has the smallest difference compared with deuterium dilution, eventhougt individual measurements are not clinically acceptable. Caution is recommended when using individual measurements of body composition in the elderly, due to large errors in the determinations