Figure 1.
z-Scores of FEV1, FVC, forced expiratory flow between 25% and 75% of the FVC, and FEV1/FVC ratio. (A) Before bronchodilator (n subjects = 706) and (B) after bronchodilator (n subjects = 689) from age 11 to age 32 years by serum CC16 (club cell secretory protein 16) tertile categories. Lung function indices were standardized separately for males and females. Error bars indicate the standard error. P values refer to the overall comparison of lung function levels across the three CC16 tertiles. FEF25–75 = forced expiratory flow between 25% and 75% of the FVC.