Reference equations for spirometry in healthy Asian children aged 5 to 18 years in Taiwan

Background and objective: This study aimed to establish reference equations for spirometry in healthy Taiwanese children and assess the applicability of the Global Lung Function Initiative (GLI)-2012 equations to Taiwanese children. Methods: Spirometric data collected from 757 healthy Taiwanese children aged 5 to 18 years in a population-based cohort study. Prediction equations derived using linear regression and the generalized additive models for location, scale and shape (GAMLSS) method, respectively. Results: The GLI-2012 South East Asian equations did not provide a close fit with mean +/- standard error z-scores of -0.679 +/- 0.030 (FVC), -0.186 +/- 0.044 (FEV1), -0.875 +/- 0.049 (FEV1/FVC ratio) and -2.189 +/- 0.063 (FEF25-75) for girls; and 0.238 +/- 0.059, -0.061 +/- 0.053, -0.513 +/- 0.059 and -1.896 +/- 0.077 for boys. The proposed GAMLSS models took age, height, and weight into account. GAMLSS models for boys and girls captured the characteristics of spirometric data in the study population closely in contrast to the linear regression models and the GLI-2012 equations. Conclusion: This study provides up-to-date reference values for spirometry using GAMLSS modeling in healthy Taiwanese children aged 5 to 18 years. Our study provides evidence that the GLI-2012 reference equations are not properly matched to spirometric data in a contemporary Taiwanese child population, indicating the urgent need for an update of GLI reference values by inclusion of more data of non-Caucasian decent.