OBJECTIVETo investigate the association of forced expiratory volume in 1 second (FEV1) and the maximum peak expiratory flow (PEF) with small airway function in asthmatic children of different ages and genders.

METHODSThis cross-sectional study was conducted among 619 asthmatic children with disease remission aged 3 to 13 years. The children were divided into 3 age groups, namely 3 to 5 years group (314 cases), 6 to 9 years group (207 cases) and 10 to 13 years group (98 cases), and their respiratory physiological parameters such as FEV1 and PEF were measured.

RESULTSOf the airway function parameters, PEF showed the highest abnormality rate (>85%) in these asthmatic children. In male and female asthmatic children aged 6 to 9 years, abnormalities in forced expiratory flow rate 25% (MEF25) showed the highest frequency (56% and 63%, respectively). In 3-5 years and 10-13 years groups, MEF25 abnormalities were the most frequent in male children (43% and 71%, respectively), whereas abnormalities in MEF50 were the most common in female children (33% and 69%, respectively). FEV1 and PEF were positively correlated to all the parameters of small airway functions in these asthmatic children (r>0.5, P<0.01) except for MEF25 in female asthmatic children aged 3 to 5 years (r=0.19, P=0.168; r=0.086, P=0.535).

CONCLUSIONIn asthmatic children, FEV1 and PEF are positively correlated to the parameters of small airway function with only the exception of MEF25 in female children aged 3 to 5 years, suggesting the value of FEV1 in the diagnosis of asthma in children.