A longitudinal study aims to identify which children with asthma are more likely to suffer a loss of lung function.
Children with nonsevere and severe asthma are more likely to have declining lung function throughout childhood and into adulthood. Yet predictors of which children will experience poor lung function in have not been thoroughly explored or identified
In a study published in August 2022 in the Journal of Allergy and Clinical Immunology, researchers used data from the Severe Asthma Research Program (SARP) 3 pediatric cohort study to discover phenotypic factors that contribute to declining lung function. SARP 3 is an ongoing longitudinal study with the goal of better understanding asthma phenotypic expressions in children and adults with mild to severe asthma.
Children were enrolled between November 2012 and January 2015. The researchers for the current study included participants with an average age of 11.5 years. A total of 111 had severe asthma, and 77 had nonsevere asthma. The researchers measured lung function at baseline and annually. The primary outcome was the absolute forced expiratory volume in 1 second (FEV1), a standard measure of lung function, at each assessment for up to 6 years. Secondary outcomes included postbronchodilator FEV1 and prebronchodilator FEV1 over forced vital capacity (FVC).
After analyzing the data, the investigators identified several factors as predictors of FEV1 changes over time, including baseline fractional exhaled nitric oxide (FeNO), response to a characterizing dose of intramuscular triamcinolone acetonide, and maximal bronchodilator responsiveness. Other factors were age, obesity, and frequency of exacerbations.
A significant study finding was the association of asthma exacerbation frequency with changes in FEV1 in boys compared with girls. The researchers found that boys who had one to two exacerbations in the previous year lost -20 mL FEV1 at each successive year. Those with three or more exacerbations during the previous year lost -34 mL FEV1 at each successive year. These associations were not present among girls in the study.
The researchers conclude that determinants of lung function in children with severe and non-severe asthma include the triamcinolone-induced difference from baseline FEV1, FeNO, maximum bronchodilator responsiveness, and obesity. They also discovered that a higher incidence of asthma exacerbations is associated with lower lung function in boys.
The authors commented that their findings offer a framework for identifying children with asthma with an increased risk of declining lung function over time.