Forest plots for (A) estimated ratio of geometric mean lung clearance index (LCI) with 95% confidence interval (CI) for children with primary ciliary dyskinesia (PCD) or cystic fibrosis (CF) compared with healthy control subjects (reference), from regression analyses of log-transformed LCI data, adjusted for height, sex, and age. (B) Estimated difference in mean spirometric measures (95% CI) between children with PCD or CF and healthy control subjects from regression analyses. *LCI 2.5 were log-transformed for linear regression because of nonnormality. The resulting exponentiated parameter estimate provides the ratio of the geometric mean of each outcome by disease group to that of healthy control subjects. For example, patients with PCD have a geometric mean LCI 2.5 that is 26% higher than that of healthy control subjects of the same age, height, sex, and ethnicity (95% CI, 15–37% higher). †Calculated using Global Lung Initiative equations. The results are interpreted as the difference in the mean measure between children with PCD or CF and healthy control subjects of the same age, height, sex, and ethnicity. For example, the mean forced expiratory volume in 1 second % predicted of children with PCD is 11.1% lower than that of healthy control subjects (95% CI, −17.6 to −4.7). FEF25–75 = forced midexpiratory flow at 25–75% of the expiratory volume; FEV1 = forced expiratory volume in 1 second; FVC = forced vital capacity.