Findings revealed that lower levels of vitamin D might cause structural changes in the airway muscles, making breathing more difficult in children with STRA.
Asthma can usually be successfully treated with low doses of corticosteroids in most children, however, approximately 5 to 10% of asthmatic children do not respond to standard treatment. Children with severe therapy-resistant asthma, or STRA, suffer more asthma episodes and asthma-related illnesses and therefore require more healthcare services compared to those children who respond to treatment.
Atul Gupta, MRCPCH, M.D., a researcher from Royal Brompton Hospital and the National Heart and Lung Institute (NHLI) at Imperial College and King's College London explained:
"This study clearly demonstrates that low levels of vitamin D are associated with poorer lung function, increased use of medication, worse symptoms and an increase in the mass of airway smooth muscle in children with STRA. It is therefore plausible that the link between airway smooth muscle mass and lung function in severe asthma may be partly explained by low levels of vitamin D."
This is the first study examining the relationship between vitamin D and the pathophysiology of children with STRA. Earlier studies of asthmatic children have already been linked to increases in airway smooth muscle mass with poorer lung function whilst in vitro studies have proven the existence of a link between vitamin D levels and the proliferation of airway smooth muscle.
Dr. Gupta clarified:
"Little is known about vitamin D status and its effect on asthma pathophysiology in these patients. For our study, we hypothesized that children with STRA would have lower levels of vitamin D than moderate asthmatics, and that lower levels of vitamin D would be associated with worse lung function and changes in the airway muscle tissue."
For the study researchers enlisted a total of 86 children; 36 children suffered from STRA, 26 had moderate asthma and 24 were non-asthmatic. They measured the relationships between vitamin D levels and lung function, medication usage and symptom exacerbations and examined tissue samples from children's airways in the STRA group to assess structural changes in the airway's smooth muscle.
Findings of the study revealed that children in the STRA group had significantly lower vitamin D levels, more exacerbations, increased use of asthma medications and poorer lung function compared with children from the two other groups. The researchers also discovered an increase in airway muscle tissue in the STRA group.
Dr. Gupta commented that:
"the results of this study suggest that lower levels of vitamin D in children with STRA contribute to an increase in airway smooth muscle mass, which could make breathing more difficult and cause a worsening of asthma symptoms."
"Our results suggest that detecting vitamin D deficiency in children with STRA, and then treating that deficiency may help prevent or reduce the structural changes that occur in the airway smooth muscle, which in turn may help reduce asthma-related symptoms and improve overall lung function."
According to Gupta the findings suggest new treatment strategies for children suffering from difficult-to-treat asthma but before any widespread treatment recommendations can be made, he said: "The determination of the exact mechanism between low vitamin D and airway changes that occur in STRA will require intervention studies. Hopefully, the results of this and future studies will help determine a new course of therapy that will be effective in treating these children."
Written by Petra Rattue