Spirometric reference values in heathy Chinese adults in Taiwan: The secular changes and comparison with other Asian populations

Background/purpose: Although the lung function test has played an important role in respiratory care for a long time, valid spirometry reference values in the Chinese population in Taiwan remain to be elucidated. Methods: 2963 healthy Taiwanese subjects aged 21 to 88 years (1765 males, 59.6%) from February 2015 to February 2017 were enrolled. The subjects attempted to meet the 2005 American Thoracic Society (ATS) and the European Respiratory Society (ERS) guidelines when performing forced expiratory spirograms. We would like to establish the spirometry predictive equations for forced expiratory volume (FEV₁), forced vital capacity (FVC), FEV₁/FVC, and lower limit of normal (LLN) in Taiwan and compare with other Asian populations. Results: We established the spirometry predictive equations using a linear model for the entire population, using age and height as independent variables, which best predicted all spirometry parameters for sea level and highland subjects. We found that the values of FEV₁ and FVC for the Taiwanese subjects in our study were systematically lower than those reported in South Korea, Japan, and China, but higher than the values in Yang's 1993 and Pan's 1997 Taiwan study. Conclusion: This study addressed the up-to-date spirometry reference equations and values for a healthy adult Chinese population in Taiwan.