PURPOSE OF THE STUDY.
Polymorphisms of the β2-adrenergic receptor (AR) gene have been associated with response to both long-acting and short-acting β agonists. Studies have suggested that patients with homozygous arginine at position 16 are more likely to have reduced bronchodilator effects, increased asthma exacerbations, or decreased pulmonary function compared with those with homozygous glycine or heterozygous glycine/arginine at the same position. Studies are contradictory, however, on the relationship between these polymorphisms and asthma exacerbations, which could be related to the severity of asthma being studied. The purpose of this study was to determine if these polymorphisms had any effect on asthma exacerbations in children with severe asthma taking higher-dose inhaled corticosteroids who are regularly receiving salmeterol.
The study population consisted of Argentinian children (N = 97) with a diagnosis of severe asthma who were genotyped for β2AR variants. All children had stable asthma and were taking medium- to high-dose inhaled corticosteroids and were placed on twice-daily albuterol during the study.
Information on asthma exacerbations, need for albuterol, courses of oral steroids, and hospital admissions was collected at monthly clinic visits over the 12-month study. The severity of asthma exacerbations was defined according to a consensus statement recently published. Pulmonary function was performed at each clinic visit. Patients were treated according to their personalized action plans.
There was no difference among genotypes in the proportion of participants with severe asthma exacerbations, the rate of asthma exacerbations, hospitalizations, or the time to first asthma exacerbation. In addition, no differences were noted in the use of albuterol or symptom-free days.
Genotypic effects on asthma control were not present among children using medium- to high-dose inhaled corticosteroids plus a long-acting bronchodilator.
This study reveals that children with severe asthma who are taking medium- to high-dose inhaled corticosteroids do not demonstrate increased asthma exacerbations or loss of asthma control on the basis of their β2AR genotype. It is possible that any effects due to a difference in genotype may have been overcome by the dose of inhaled corticosteroids.
- Copyright © 2013 by the American Academy of Pediatrics