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

Background: Accurate spirometry reference equations are essential for diagnosing and managing respiratory conditions in children. Although the GLI Global Equations have been proposed for general use, there were few Asian populations available for inclusion. This study aims to develop and validate spirometric reference equations for healthy Chinese children.

Methods: From May 2018 to May 2021, a cross-sectional study involving healthy Chinese Han children aged 4 to 18 years was conducted by 33 research centers across 24 regions in China. Participants were recruited directly from schools, and physical growth indices (height, weight) were measured. Spirometry tests were performed and demographic and medical history data were collected through questionnaires. New prediction equations were developed using multiple linear regression models with age, height, and weight as predictors. And comparisons were made with existing Caucasian and Chinese pediatric reference equations.

Results: Lung function was assessed in 8929 healthy Chinese Han children. Age, weight, and height emerged as strong predictors of lung function (p < 0.001), and sex-specific reference equations incorporating these factors demonstrated high accuracy in internal validation, yielding mean z-scores within a narrow range of -0.004 to -0.069. In comparison, the Zapletal equations overestimated FEV and FEV/FVC while underestimating other lung function parameters. Additionally, the GLI equations underestimated lung function parameters, including FEV, FVC, and FEV/FVC, for both boys and girls. Compared to previous Chinese studies, the z-scores in this study ranged from - 0.97 to 0.93, with some cases showing significant deviations, highlighting the limitations of existing equations.

Conclusion: This study developed new spirometry reference equations tailored for healthy Chinese children, with differences noted compared to existing equations. These equations reflect contemporary growth patterns and regional diversity in China, providing an additional option for clinical use.

Trial Registration: NO.: ChiCTR: 1,800,019,029. Registered 22 October 2018.