Obesity and bronchial obstruction in impulse oscillometry at age 5-7 years in a prospective post-bronchiolitis cohort

Background and AimsObesity has been linked with asthma symptoms, need for asthma treatment and reduced lung function but not with increased bronchial reactivity in children. The aim of this study was to evaluate the association between previous or current weight status and current lung function and bronchial reactivity to exercise at early school age. MethodsNinety-nine children hospitalized for bronchiolitis at the age of less than 6 months were studied with impulse oscillometry (IOS) at the mean age of 6.3 years. Data on birth weight and weight gain in infancy before hospitalization were collected during hospitalization. Current weight and height data were transformed into age- and sex-specific height-related body mass index z scores (zBMI) using the Finnish national population-based weight and height data as reference. ResultsSome significant though only low or modest correlations were found between current zBMI and baseline, post-exercise and post-bronchodilator IOS values in adjusted linear regression analysis. Seven obese children by zBMI had higher post-bronchodilator airway impedance (Zrs) and resistance (Rrs) at 5Hz and lower post-bronchodilator frequency dependency of resistance (dRrs/df) than normal weight children. There were no significant differences in responses to exercise or to bronchodilators between currently obese or overweight children and normal weight children. Birth weight less than 3,000g was associated with larger exercise-induced changes in Zrs and Rrs at 5Hz, and in reactance (Xrs) at 5Hz, than those with birth weight more than 3,000g. ConclusionsPreliminary evidence was found that obesity may be associated with airway obstruction, but not with bronchial hyper-reactivity. Pediatr Pulmonol. 2015; 50:908-914. (c) 2014 Wiley Periodicals, Inc.