Estimating body composition from skinfold thicknesses and bioelectrical impedance analysis in cystic fibrosis patients.
BACKGROUND
The accuracy of body composition estimates based on skinfold thickness measurements and bioelectrical impedance analysis (BIA) is not yet adequately explored in cystic fibrosis (CF). Using DXA as reference method we verified the accuracy of these techniques and identified predictors of body composition specific for CF.


METHODS
One hundred forty-two CF patients (age range: 8-31 years) underwent a DXA scan. Body fat percentage (BF%) was estimated from skinfolds, while fat free mass (FFM) from single-frequency 50 kHz BIA.


RESULTS
Bland-Altman analysis showed poor intra-individual agreement between body composition data provided by DXA and BF% estimated from skinfolds or FFM estimated from BIA. The skinfolds of the upper arm were better predictors of BF% than BMI, while compared to other BIA measurements the best predictor of FFM was the R-index (Height(2)/Resistance).


CONCLUSIONS
Due to poor accuracy at individual level, the estimates of body composition obtained from these techniques cannot be part of the standard nutritional assessment of CF patients until reliable CF-specific equations will become available. BMI has limited value in predicting body fatness in CF patients and should be used in combination with other predictors. Skinfolds of the upper arm and R-index are strongly related to BF% and FFM and should be tested in a large CF population to develop specific predictive equations.
Department of Paediatrics, Cystic Fibrosis Center, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy.
Gianfranco
G
Alicandro
International Center for the Assessment of Nutritional Status, University of Milan, Milan, Italy.
Alberto
A
Battezzati
Bone Metabolism Unit, Istituto Auxologico Italiano IRCCS, Milan, Italy.
Maria Luisa
ML
Bianchi
Department of Paediatrics, Cystic Fibrosis Center, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy.
Silvana
S
Loi
Department of Paediatrics, Cystic Fibrosis Center, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy.
Chiara
C
Speziali
Department of Paediatrics, Cystic Fibrosis Center, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy.
Arianna
A
Bisogno
Department of Paediatrics, Cystic Fibrosis Center, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy. Electronic address: carla.colombo@unimi.it.
Carla
C
Colombo
D000293:Adolescent; D000328:Adult; D001823:Body Composition; D002648:Child; D003550:Cystic Fibrosis / Q000175:diagnosis*; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008297:Male; D012885:Skinfold Thickness; D055815:Young Adult
Bioelectrical impedance analysis; Body composition; Cystic fibrosis; DXA; Skinfold thicknesses