Effect of obesity on pulmonary function in asthmatic children of different age groups

Abstract

To study the effect of obesity on pulmonary function in newly diagnosed asthmatic children of different age groups. Two hundred and ninety-four children with newly diagnosed asthma were classified into preschool-age (<6 years) and school-age (6 to 12.5 years) groups. They were then classified into obese, overweight, and normal-weight subgroups based on their body mass index (BMI). All the children underwent pulmonary function tests, including large airway function tests [forced vital capacity (FVC%) and forced expiratory volume in one second (FEV1%)] and small airway function tests [maximal expiratory flow at 25% of vital capacity (MEF25%), maximal expiratory flow at 50% of vital capacity (MEF50%), and maximal expiratory flow at 75% of vital capacity (MEF75%)]. The school-age group showed lower FEV1%, MEF25%, and MEF50% than the preschool-age group (P<0.05) after adjustment for sex and BMI. The normal-weight children in the school-age group had lower FEV1%, MEF25%, and MEF50% compared with their counterparts in the preschool-age group (P<0.05). The overweight children in the school-age group showed lower FVC% and MEF50% than those in the preschool-age group. However, all the pulmonary function parameters showed no significant differences between the obese children in the preschool-age and school-age groups. In the preschool-age group, FVC%, FEV1%, and MEF75% of the obese children were lower than those of the normal-weight children. In the school-age group, only FVC% and FEV1% showed differences between the obese and normal-weight children (P<0.05). The effect of obesity on the pulmonary function varies with age in children with asthma, and the effect is more obvious in those of preschool age.