AUTHOR=Sheikh Saba , Zemel Babette S. , Stallings Virginia A. , Rubenstein Ronald C. , Kelly Andrea TITLE=Body Composition and Pulmonary Function in Cystic Fibrosis JOURNAL=Frontiers in Pediatrics VOLUME=2 YEAR=2014 URL=https://www.frontiersin.org/journals/pediatrics/articles/10.3389/fped.2014.00033 DOI=10.3389/fped.2014.00033 ISSN=2296-2360 ABSTRACT=

Background: Lower body mass index (BMI) is associated with worse pulmonary function in cystic fibrosis (CF). Hypothesis: lean body mass (LBM) is more strongly associated with pulmonary function than BMI is.

Methods: Anthropometrics, body composition by dual x-ray absorptiometry, and pulmonary function were determined in pancreatic insufficient CF (PI-CF) youth. Sex and age-adjusted Z-scores (BMI-Z, LBMI-Z, FMI-Z) were generated for CF and controls. (1) Associations of BMI-Z with LBMI-Z and FMI-Z and (2) age-adjusted associations of BMI-Z, LBMI-Z, and FMI-Z with FEV₁%-predicted were tested.

Results: Two hundred eight PI-CF subjects had lower BMI-Z, LBMI-Z, and FMI-Z compared to 390 controls. BMI-Z was associated with lower LBMI-Z (p < 0.0001) in PI-CF. In females, LBMI-Z and BMI-Z were positively associated with FEV₁%-predicted; this relationship did not persist for FMI-Z after adjustment for LBMI-Z. In males, only LBMI-Z and BMI-Z were associated with FEV₁%-predicted.

Conclusion: In PI-CF youth, deficits in LBM were apparent. At lower BMI percentiles, BMI may not accurately depict LBM in PI-CF. In under-nourished PI-CF youth, this preservation of FM in preference to LBM is relevant since LBMI-Z, but not FMI-Z, is positively associated with FEV₁%-predicted. Lean body mass index is more strongly associated with lung function compared to BMI, especially in the under-nourished child and adolescent with PI-CF.