Bioelectrical impedance in young patients with cystic fibrosis: Validation of a specific equation and clinical relevance.
Body composition (BC) analysis based on bioelectrical impedance analysis (BIA) provides conflicting results. The purpose of the study was to validate an equation specific for young patients with cystic fibrosis (CF), describe their BC and investigate its association with lung function.



Fifty-four young CF patients were evaluated by BIA and dual X-ray absorptiometry (DXA). An empirically derived CF-specific equation for fat-free mass (FFM) estimation by BIA was elaborated after stepwise multivariate regression and the agreement between BIA and DXA was assessed by Bland-Altman plots. The association between BC and lung function was investigated by regression analysis.



The mean difference between the BIA and DXA assessment was close to zero. A total of 22.5% of patients (n=9) presented a FFM z-score≤-2. They had a worse pulmonary function and diaphragmatic impairment. Among these 9 patients, 7 had a normal BMI z-score>-1.



BIA, based on a CF-specific equation, is a reliable method for BC assessment and allows the identification of patients at risk of nutritional degradation and bad respiratory prognosis.
Pediatric Pulmonology Department, Hôpital Universitaire Necker Enfants Malades, Paris, France.
A M
AM
Charatsi
Pediatric Pulmonology Department, Hôpital Universitaire Necker Enfants Malades, Paris, France.
P
P
Dusser
Bio-statistics Department, Hôpital Universitaire Necker Enfants Malades, Paris, France.
R
R
Freund
Physiology Department, Hôpital Universitaire Necker Enfants Malades, Paris, France.
G
G
Maruani
Aminogram, La Ciotat, France.
H
H
Rossin
Physiology Department, Hôpital Universitaire Necker Enfants Malades, Paris, France.
A
A
Boulier
Pediatric Pulmonology Department, Hôpital Universitaire Necker Enfants Malades, Paris, France.
M
M
Le Bourgeois
Pediatric Pulmonology Department, Hôpital Universitaire Necker Enfants Malades, Paris, France.
F
F
Chedevergne
Pediatric Pulmonology Department, Hôpital Universitaire Necker Enfants Malades, Paris, France.
J
J
de Blic
Aminogram, La Ciotat, France.
A
A
Letourneur
Pediatric Pulmonology Department, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, Brussels, Belgium.
G
G
Casimir
Bio-statistics Department, Hôpital Universitaire Necker Enfants Malades, Paris, France.
J P
JP
Jais
Pediatric Pulmonology Department, Hôpital Universitaire Necker Enfants Malades, Paris, France. Electronic address: isabelle.sermet@nck.aphp.fr.
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I
Sermet-Gaudelus
D015502:Absorptiometry, Photon / Q000379:methods; D000293:Adolescent; D001823:Body Composition; D015992:Body Mass Index; D002648:Child; D003550:Cystic Fibrosis / Q000175:diagnosis / Q000503:physiopathology; D017097:Electric Impedance; D005260:Female; D005602:France; D006801:Humans; D008297:Male; D011379:Prognosis; D011446:Prospective Studies; D012129:Respiratory Function Tests / Q000379:methods; D013223:Statistics as Topic; D055815:Young Adult
Bioelectrical impedance analysis; Body composition; Cystic fibrosis; Diaphragm; Fat-free mass; Lung function