Normal Predicted Reference Values for Spirometry in Korean Children and Adolescents

Pulmonary function tests are useful to evaluate airway obstructions and bronchial responsiveness. We aimed to determine the reference values applicable to Korean children and adolescents. In total, 5590 (2607 males, 2983 females) healthy children aged 4 to 17 years old were recruited from three regions in Korea. Simple and multiple regression analyses were applied using age, height, and weight as variables to predict the forced vital capacity (FVC), forced expiratory volume in one second (FEV(1)), maximum mid-expiratory flow (MMEF) and the peak expiratory flow rate (PEFR). There were significant correlations between the variables and parameters (P < 0.001). The coefficient of determination (R(2)) values of polynomial equations with two variables were lower than those with two variables but higher than those of monomial equations based on height. The prediction equations by height were obtained, and the R(2) value of the FEV(1) was the highest. The predicted spirometric values for males were higher than those for females except for the MMEF. The R(2) values for the FEV1 and FVC were higher than previous studies except for the R(2) value of the FVC for males in European data. This study provided updated regression equations of normal predicted values for spirometry applicable to Korean children and adolescents.