Bronchiolitis in Early Infancy Is Associated With Irreversible Airway Obstruction in Young Adulthood

Background: Childhood risk factors, such as bronchiolitis, have been associated with airway obstruction later in life. However, assessing childhood risk factors for airway obstruction in adulthood requires long follow-ups with carefully gathered data. Our long-term follow-up represents lung function in early adulthood after infant bronchiolitis with evaluation of asthma and tobacco smoke exposure as childhood risk factors. Methods: We prospectively followed 166 term children hospitalized for bronchiolitis under 6 months of age. Lung function was measured at the mean age of 18.3 years by spirometry on 72 former bronchiolitis patients and 28 controls. We compared z-scores of FEV1 (forced expiratory volume in first second), FVC (forced vital capacity), and FEV1/FVC before and after bronchodilation. Reversibility was tested as FEV1 change in the bronchodilation test. The roles of asthma and smoke exposure were controlled in the analysis. Results: FEV1/FVC was lower in cases versus controls at baseline (mean z-score −0.90, SD 1.40 vs 0.10 SD 1.17; p = 0.001) and after bronchodilatation (0.54, SD 1.06 vs. −0.05, SD 1.22; p = 0.028). FEV1 increase in the bronchodilation test was greater in cases versus controls (6.3%, SD 5.3 vs. 2.3%, SD 3.7; p = 0.001). After excluding subjects with current asthma, the differences remained significant in baseline and post-bronchodilator FEV1/FVC and in FEV1 change in bronchodilation test, and after adjusting for previous asthma and household smoking, the differences remained significant in baseline and post-bronchodilator FEV1/FVC. Conclusion: Lower FEV1/FVC after bronchodilation in cases suggests a risk of irreversible obstructive lung function in young adults after infant bronchiolitis.