Abstract

MARTIN MORENO, V. et al. Interchangeability of the fat-to-fat-free mass ratios obtained by arm anthropometric measures, skinfold thickness and bioelectrical impedance . Nutr. Hosp. [online]. 2003, vol.18, n.2, pp.77-86. ISSN 1699-5198.

Background: Body fat, fat free mass and the relationship between both, the fat-to-fat-free mass ratio are useful parameters in the nutritional evaluation of the patient. The aim of this study is to evaluate the degree of agreement among the fat-to-fat-free mass ratios obtained by arm anthropometric measures (fat-muscle index, FMI), Siri equation for the sum of four skinfold thickness (body fat-muscle index, BFMI_Siri) and triceps skinfold (BFMI_triceps) and bioelectrical impedance (BFMI_Omron) methods. Methods: This is a cross-sectional study. A total of 145 patients were evaluated by anthropometry and bioelectrical impedance (Omron BF 300⁽), being estimated the agreement through the Intraclass Correlation Coefficient (ICC) and Bland-Altman method. The reference method was BFMI_Siri. Results: The ICC between BFMI_Siri - BFMI_triceps were 0,9304 (0,9035; 0,9498), between BFMI_Siri - FMI of 0,7726 (0,6846; 0,8361) and between BFMI_Siri - BFMI_Omron of 0,9114 (0,8771; 0,9361). BFMI_triceps (limits of agreement -0,171 to 0,117) show the best agreement according to Bland-Altman analysis with BFMI_Siri, followed by BMFI_Siri - BFMI_Omron (-0,186; 0,178). The agreement limits between FMI and BFMI_Siri (-0,2; 0,42), BFMI_triceps (-0,26; 0,42) or BFMI_Omron (-0,292; 0,504) were beyond of the established cut-off points (-0,2; 0,2). Conclusions: Due to the nature of the statistical agreement BFMI_triceps and BFMI_Omron are methods interchangeable methods between them and with BFMI_Siri. FMI is not interchangeable with BFMI_Siri, BFMI_Omron or BFMI_triceps. These results suggest that FMI cannot estimate properly the body composition. BFMI_triceps and BFMI _Omron are valid alternative methods to be used instead BFMI_Siri in the fat-to-fat-free mass ratio assessment.

Keywords : Anthropometry; Bioelectrical impedance; Body fat; Body composition; Fat-to-fat-free mass ratio; Skinfold thickness.

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