title: Body composition by hydrometry (deuterium oxide dilution) and bioelectrical impedance in subjects aged >60 y from rural regions of Cuba, Chile and Mexico.
abstract: BACKGROUND
  In Latin American and Caribbean countries such as Chile, Mexico and Cuba, the population over 60 y has increased steadily. In this age group, there is scarce information about body composition, particularly for those living in rural areas.
  
  
  OBJECTIVE
  The purpose of this study was to determine body composition in free-living and healthy elderly subjects >60 y from rural areas of Chile, Cuba and Mexico using deuterium oxide dilution and bioelectrical impedance (BIA) and to develop and cross-validate a predictive equation for this group of subjects by BIA for future use as a field technique.
  
  
  METHODS
  The study included 133 healthy subjects (73 males and 60 females) >60 y from rural regions of Cuba, Chile and Mexico.
  
  
  METHODS
  Total body water, body weight, height and other anthropometric and BIA variables (resistance and reactance) were measured.
  
  
  METHODS
  Total body water was determined by deuterium oxide dilution, and fat-free mass (FFM)/fat mass were derived from this measurement. The total sample was used in a split-sample internal cross-validation. BIA and other anthropometric variables were integrated to multiple regression model to design the best predictive equation, which was validated in the other sample. ANOVA, multiple regression and Bland and Altman's procedure were used to analyze the data.
  
  
  RESULTS
  Body weight, percentage of fat and fat-free mass were lower in the Cuban men and women compared with Chilean and Mexican men and women. The best predictive equation of the FFM was: FFM kg=(-7.71+(H(2)/R x 0.49)+(country or ethnicity x 1.12)+(body weight x 0.27)+(sex x 3.49)+(Xc x 0.13)), where H(2) is height(2) (cm); R is resistance (Omega); country: Chile=1, Mexico=2 and Cuba=3; sex: women=0 and men=1; body weight (kg) and Xc is reactance (Omega). R(2) was 0.944 and the root mean square error (RMSE) was 2.08 kg. The mean+/-s.d. of FFM prediction was 44.2+/-9.2 vs 44.6+/-10.1. The results of cross-validation showed no significant difference with the line of identity, showing that the predicted equation was accurate. The intercept (=-0.32) was not significantly different from zero (P=0.89) and the slope (=1.02) not significantly different from 1.0 (P>0.9). The R(2) was 0.86, RMSE=3.86 kg of FFM and the pure error was 3.83.
  
  
  CONCLUSIONS
  The new BIA equation is accurate, precise and showed good agreement. The use of this equation could improve the estimates of body composition for the elderly population for these regions, as well as enhancing the opportunity to conduct studies in the elderly population from Latin America.
authors.affiliation: División de Nutrición, Centro de Investigación en Alimentación y Desarrollo, A.C., Hermosillo, Sonora, México. mauro@cascabel.ciad.mx
authors.forename: M E
authors.initials: ME
authors.lastname: Valencia
authors.forename: H
authors.initials: H
authors.lastname: Alemán-Mateo
authors.forename: G
authors.initials: G
authors.lastname: Salazar
authors.forename: M
authors.initials: M
authors.lastname: Hernández Triana
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D001823:Body Composition / Q000502:physiology*; D002677:Chile; D003462:Cuba; D017666:Deuterium Oxide; D017097:Electric Impedance; D005260:Female; D006801:Humans; D007201:Indicator Dilution Techniques; D008297:Male; D008800:Mexico; D008875:Middle Aged; D009765:Obesity / Q000175:diagnosis; D012424:Rural Population
chemical_list: D017666:Deuterium Oxide