OBJECTIVETo study the effect of obesity on pulmonary function in newly diagnosed asthmatic children of different age groups.

METHODSTwo 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%)].

RESULTSThe 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).

CONCLUSIONSThe 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.