SAN FRANCISCO – Children with recurrent, severe virus-induced wheezing during their first 3 years of life had significantly reduced prebronchodilator lung function at school age, compared with children with no history of wheezing, but no differences were seen on tests of postbronchodilator lung function, based on data from 215 children.
Previous studies have shown that early childhood is a vulnerable time for the development of lung function, and recurrent wheezing can be a major risk factor for reduced lung function when children reach school age, said Dr. Daniel Jackson of the University of Wisconsin, Madison, and his colleagues.
“This is particularly important because loss of lung function is associated with morbidity and limitation due to asthma,” Dr. Jackson said in an interview.
The researchers reviewed data from the Childhood Origins of Asthma (COAST) study, a prospective study of children at increased risk for allergies or asthma. They divided the children into four groups according to their wheezing history. The groups consisted of 101 children with no wheezing, 69 children with wheezing who received no oral corticosteroids, 23 children who received corticosteroids with one episode of wheezing, and 22 children who received corticosteroids with two or more episodes of wheezing. Pre- and postbronchodilator spirometry was performed each year to check lung function and compare lung volume among the groups, according to the researchers' poster, which was presented at the meeting.
Overall, prebronchodilator forced expiratory volume in 0.5 and 1 second (FEV0.5 and FEV1) obtained at age 5-8 years were significantly lower in children with histories of multiple wheezing episodes treated with oral steroids, compared with each of the other groups, after the investigators controlled for asthma, age, sex, height, weight, race, and smoke exposure. The children with two or more wheezing episodes treated with oral steroids had an average FEV1 of 1.26 L, compared with 1.37 L in children with no episodes of wheezing, 1.34 L in children who had wheezing without oral steroid treatment, and 1.38 L in children who had wheezing with one oral steroid treatment.
However, postbronchodilator measures taken at 6-8 years were not significantly different in children with repeated wheezing episodes, compared with children with fewer or no wheezing episodes.
The findings suggest that reduced lung function in school-aged children at high risk for asthma is at least partially reversible, the researchers noted. “Whether these severe wheezing episodes caused progressive lung function or were due to low baseline lung function is not known,” they wrote. But the results also suggest that preventing severe wheezing in early childhood could reduce later problems caused by a loss of lung function, and new therapeutic strategies are needed to prevent virus-induced wheezing in high-risk children, they added.