Preschool Impulse Oscillometry Predicts Active Asthma and Impaired Lung Function at School Age

BACKGROUND:Asthmatic symptoms often start during early childhood. Impulse oscillometry (IOS) is feasible in preschool children who may be unable to reliably perform spirometry measurements. OBJECTIVE:We evaluated the utility of IOS in a multicenter multiethnic high-risk asthma cohort entitled the Vitamin D Antenatal Asthma Reduction Trial (VDAART). METHODS:The VDAART recruited pregnant women whose children were followed from birth to age 8 years. Lung function was assessed with IOS at ages 4, 5, and 6 years and spirometry at ages 5, 6, 7, and 8 years. Asthma status, respiratory symptoms, and medication use were assessed with repeated questionnaires from birth to age 8 years. RESULTS:In total 220 children were included in this secondary analysis. Recent respiratory symptoms and short-acting β2-agonist (SABA) use were associated with increased respiratory resistance at 5 Hz (R5) at age 4 years (β 2.6; 95% CI 1.0, 4.4; P=0.002 and β 3.4; 95% CI 0.7, 6.2; P=0.015, respectively). Increased R5 at age 4 years was also associated with decreased lung function from ages 5 to 8 years (β -0.3; 95% CI -0.5, -0.1; P<0.001 for FEV1 at 8 years) and active asthma at age 8 years (β 2.0; 95% CI 0.2, 3.8; P=0.029). CONCLUSION:Increased respiratory resistance in preschool IOS is associated with frequent respiratory symptoms as well as school-age asthma and lung function impairment. Our findings suggest that IOS may serve as a potential objective measure for early identification of children who are at high risk of respiratory morbidity.