Does lung function change in the months after an asthma exacerbation in children?

Introduction: There are limited data describing lung function changes in children after an asthma exacerbation. Our hypothesis was that lung function does not fully recover in children in the months following an asthma exacerbation. Methods: Data were analysed from RCTs where children with asthma had spirometry measured at 3-month intervals over a year. Our first approach used mixed level models to compare spirometry measured on 2 occasions 3-months apart (assessments 1 and 2) before a single exacerbation to measurements made on two occasions after the exacerbation (assessments 3 and 4), with adjustment for covariates. We then described characteristics of individuals after stratification by tertiles of change in FEV1 between assessments 2 and 3. Finally we used data from all individuals to describe changes in spirometry over a year in groups stratified by the presence of zero (n=580), one (n=165) or >one (n=64) exacerbations within a 3-month period. Results: For the 113 children who had a single exacerbation, spirometry measurements at assessment 3 or 4 did not differ from assessments 1 or 2. When stratified into tertiles by change in %FEV1 between assessments 2 and 3, those with the greater reduction were more likely to be treated with long acting beta agonist, but in this category %FEV1 at assessment 4 had returned to the value at assessment 1. %FEV1 did not change over a 12 month period within and between the three exacerbation categories. Conclusion: One or more asthma exacerbation was not associated with a fall in lung function for the whole population. Lung function does fall after an exacerbation in some individuals but returns to pre-exacerbation values within six months.