title: Predictive capacity of different bioelectrical impedance analysis devices, with and without protocol, in the evaluation of adolescents.
abstract: OBJECTIVE
  this study was performed to determine the predictive capacity of four different bioelectrical impedance analysis (BIA) devices in the assessment of adolescents, with and without a protocol.
  
  
  METHODS
  a cross-sectional study was performed with 215 adolescents aged 10 to 14 years, of both genders, evaluated through anthropometry and body composition by dual energy X-ray absorptiometry (DXA) and by four different BIA devices, with and without a protocol. The following tests were used: Kolmogorov-Smirnov's, chi-squared, Student's t or Mann-Whitney's, Kruskal-Wallis's, Wilcoxon's, and kappa index. The ROC curves were constructed and the sensitivity, specificity, and positive and negative predictive values were calculated.
  
  
  RESULTS
  of the 215 adolescents, 44.2% had excessive body fat. The tetrapolar BIA device equipped with eight tactile electrodes showed more sensitivity and results that were closer to those obtained by DXA (area under the ROC curve [AUC] = 0.964 with protocol and AUC = 0.973 without protocol, p < 0.001), as well as greater agreement (k = 0.67 with protocol and k = 0.63 without protocol, p < 0.001). The evaluation without protocol was similar to that by DXA in most investigated situations (p > 0.05).
  
  
  CONCLUSIONS
  BIA is capable of predicting alterations in adolescents' body composition. When it is impossible to perform the assessment with a protocol, its results may be useful in population studies.
authors.affiliation: Department of Nutrition and Health, Universidade Federal de Viçosa, Viçosa, MG, Brazil. Electronic address: vivian.goncalves@ufv.br.
authors.forename: Vivian Siqueira Santos
authors.initials: VS
authors.lastname: Gonçalves
authors.forename: Eliane Rodrigues de
authors.initials: ER
authors.lastname: Faria
authors.forename: Sylvia do Carmo Castro
authors.initials: Sdo C
authors.lastname: Franceschini
authors.forename: Silvia Eloiza
authors.initials: SE
authors.lastname: Priore
mesh_terms: D015502:Absorptiometry, Photon / Q000295:instrumentation*; D050154:Adiposity / Q000502:physiology*; D000293:Adolescent; D001823:Body Composition / Q000502:physiology*; D015992:Body Mass Index; D016009:Chi-Square Distribution; D002648:Child; D002985:Clinical Protocols / Q000592:standards*; D003430:Cross-Sectional Studies; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D018709:Statistics, Nonparametric
keywords: Adolescent health; Body composition; Composição corporal; Electric impedance; Impedância elétrica; Obesidade; Obesity; Saúde do adolescente