Reply to Guo et al

Wang et al respond to comments from Dr. Guo and colleagues on their work published in an issue of the Journal regarding the plasticity of individual lung function states from childhood to adulthood. They state that they fully agree that the repeatability of lung function measurements needs to be considered carefully, especially in younger children who may face challenges with the technique. Lung function measures in this study were performed according to standard American Thoracic Society-European Respiratory Society guidelines, which include criteria for repeatability. Besides, the fit of Global Lung Function Initiative z-scores at each age point was taken into account in the longitudinal analysis according to methods previously applied in large-scale studies.