Recurrent pulmonary exacerbations are associated with low fat free mass and low bone mineral density in young adults with cystic fibrosis

Abstract

Background: In cystic fibrosis (CF), systemic inflammation and pulmonary infections sustain a catabolic response leading to fat free mass (FFM) depletion.

Objectives: To investigate the association between recurrent pulmonary exacerbations and alteration in body composition in young adults with CF.

Methods: In a retrospective study we collected body composition data, obtained by DXA scan, on 85 young adults with CF (44 males, mean age 23±4years). Whole body and appendicular FFM were divided by height squared to obtain FFM indices (FFMI). Number of pulmonary exacerbations occurred in the year preceding DXA scan were computed and patients were defined as frequent exacerbators if they experienced more than 2 pulmonary exacerbations/year. Body composition data were compared between frequent and infrequent exacerbators.

Results: Male patients classified as frequent exacerbators had lower total body bone mineral density (Z-score -1.44±1.22 vs. -0.66±0.92, P=0.033), whole body FFMI (18.0±1.9kg/m(2) vs. 19.3±1.4kg/m(2), P=0.024) and appendicular FFMI (7.8±1.0kg/m(2) vs. 8.8±0.8kg/m(2)P=0.004) compared to infrequent exacerbators. The reduced FFM found in frequent exacerbators was not uniformly distributed and involved mainly appendicular FFM (mean difference: -11% compared to infrequent exacerbators, P=0.016), whereas trunk FFM was not significantly affected by pulmonary exacerbations (mean difference -3% compared to infrequent exacerbators, P=0.34). These differences were not found in female patients.

Conclusions: Recurrent pulmonary exacerbations are associated with reduced appendicular FFM and bone mineral density in young male adults with CF. The gender-dependent relationship between pulmonary exacerbations and body composition alteration needs to be further investigated.

Keywords: Body composition; Cystic fibrosis; DXA; Pulmonary exacerbations.