Am J Respir Crit Care Med. 2011 (Sep 15) [Epub ahead of print]
Atul Gupta1, Alies Sjoukes, David Richards, Winston Banya,
Catherine Hawrylowicz, Andrew Bush, and Sejal Saglani
Royal Brompton hospital,
London, United Kingdom;
King's College London,
London, United Kingdom.
This study evaluated serum vitamin D and lung function in 86 children. 25[OH]D3 levels were significantly lower in children with severe therapy resistant asthma (STRA) compared to those with moderate asthma or controls. Higher 25[OH]D3 levels were associated with improved lung function and the authors suggest that vitamin D supplementation may be useful in pediatric STRA.
Rationale Little is known about vitamin D status and its effect on asthma pathophysiology in children with severe, therapy resistant asthma (STRA). Relationships between serum vitamin D, lung function, and pathology were investigated in pediatric STRA.
Methods Serum 25-hydroxyvitamin D (25[OH]D3) was measured in 86 children (mean age 11.7 years), 36 STRA, 26 moderate asthmatics (MA) and 24 non-asthmatic controls. Relationships between 25[OH]D3, the asthma control test (ACT), spirometry, corticosteroid usage, and exacerbations were assessed. 22/36 children with STRA underwent fibreoptic bronchoscopy, bronchoalveolar lavage and endobronchial biopsy with assessment of airway inflammation and remodeling.
Results 25[OH]D3 levels (median [IQR]) were significantly lower in STRA (28[22-38])nmol/L than MA (42.5[29-63])nmol/L and controls (56.5[45-67])nmol/L (p<0.001). There was a positive relationship between 25[OH]D3 levels and %predicted forced expired volume (FEV1) (r=0.4, p<0.001) and forced vital capacity (FVC) (r=0.3, p=0.002) in all subjects. 25[OH]D3 levels were positively associated with ACT (r=0.6, p<0.001), and inversely associated with exacerbations (r=-0.6, p<0.001) and inhaled steroid dose (r=-0.39, p=0.001) in MA & STRA. Airway smooth muscle (ASM) mass, but not epithelial shedding or reticular basement membrane thickness, was inversely related to 25[OH]D3 levels (r=-0.6, p=0.008). There was a positive correlation between ASM mass and bronchodilator reversibility (r=0.6, p=0.009) and an inverse correlation between ASM mass and ACT (r=-0.7, p<0.001)
Conclusions Lower vitamin D levels in children with STRA were associated with increased ASM mass, worse asthma control and lung function. The link between vitamin D, airway structure and function suggests vitamin D supplementation may be useful in pediatric STRA.