Reference equations of pulmonary function testing for healthy Chinese children aged 4-18 years

Abstract Background Establishing accurate spirometry reference values for Chinese children is essential for diagnosing and managing respiratory conditions. This study aims to develop spirometric reference values for healthy Chinese children. Methods A cross-sectional study involving healthy children aged 4 to 18 years from 33 research centers across 24 regions in China was conducted. Physical growth indices were measured and spirometry tests were conducted. New prediction equations were developed using multiple linear regression models with age, height, and weight as predictors. Comparisons were made with existing Caucasian and Chinese pediatric reference equations, including the Zapletal and GLI-2012/2022 equations. Results Lung function was assessed in 8929 healthy Chinese children aged 4 to 18 years. In our individuals, sex, age, height, and weight were significant predictors of lung function (p < 0.001), and internal validation revealed that sex-specific reference equations based on these three factors were fairly reliable. Negative mean z-scores in the forced vital capacity (FVC), peak expiratory flow (PEF), forced expiratory flow between 25% and 75% of FVC (FEF25-75%), and positive mean z-scores in forced expiratory volume in one second (FEV1) and FEV1/FVC ratio were observed when adopting the Zapletal equations. According to the GLI-2012 and GLI-2022 equations, positive mean z-scores were observed in FEV1 and FVC in both sexes. In contrast, negative mean z-scores were observed in the FEV1/FVC ratio when applying the GLI-2012 equations. Compared with this study, the z-score of previous Chinese studies ranged from − 3.421 to 18.109, which were found to significantly overestimate or underestimate lung function parameters. Conclusion Current reference equations for spirometry in healthy Chinese children have been investigated in this study. These present a chance to improve lung disease diagnosis and treatment for both acute and chronic conditions in this sizable and susceptible population.