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

Background: 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: We used a data set of children with asthma where lung function (including FEV₁, FEV₁/FVC ratio and FEF_25-75) was measured at 3-month intervals over a year. Mixed-level models compared spirometry measured on two occasions 3 months apart before a single exacerbation (assessments 1 and 2) with measurements made on two occasions after the exacerbation (assessments 3 and 4), with adjustment for covariates. Changes in spirometry over a year were also analysed across those with exacerbations in no, one or more than one 3-month periods. 

Results: For the 113 children who had a single exacerbation, spirometry measured at assessments 1 or 2 did not differ from measurements at assessments 3 or 4 when the whole population was considered. 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 (n = 809). 

Conclusion: One or more asthma exacerbation was not associated with a fall in lung function for the whole population. In a subset of individuals, lung function does fall after an exacerbation but returns to pre-exacerbation values after a period of months.