RT Journal Article SR Electronic T1 Lung structure–function correlation in patients with primary ciliary dyskinesia JF Thorax JO Thorax FD BMJ Publishing Group Ltd and British Thoracic Society SP 339 OP 345 DO 10.1136/thoraxjnl-2014-206578 VO 70 IS 4 A1 Mieke Boon A1 Francois L Vermeulen A1 Willem Gysemans A1 Marijke Proesmans A1 Mark Jorissen A1 Kris De Boeck YR 2015 UL http://thorax.bmj.com/content/70/4/339.abstract AB Background Primary ciliary dyskinesia (PCD) is a rare disease, characterised by chronic airway infection. In cystic fibrosis, FEV1 is insensitive to detect patients with structural damage, and Lung Clearance Index (LCI) was proposed as a better marker of early lung damage. In PCD, the relationship between functional and structural abnormalities has been less studied. We aimed to re-examine this in a cohort of children and adults with mild to moderate PCD. Methods Thirty-eight patients with PCD (5.2–25.0 years) and 70 healthy controls (4.4–25.8 years) were recruited to compare LCI, measured by N2 multiple breath washout and FEV1 in a prospective observational trial. In a subset of 30 patients who underwent chest imaging, structural abnormalities were evaluated with cystic fibrosis computed tomography (CFCT) scores. Results LCI was abnormal in 28 of 38 patients and a moderate correlation was observed between LCI and FEV1 (r=−0.519, p=0.001). Moreover, LCI correlated well with CFCT total score (r=0.800, p<0.001) and also with subscores for airway wall thickening (r=0.809, p<0.001), mucus plugging (r=0.720, p<0.001) and bronchiectasis (r=0.494, p<0.001). Concordance was seen between LCI and CFCT in 25 of 30 (83%) patients, but between FEV1 and CFCT in only 16 of 30 (53%) patients. LCI was more sensitive (90.9%, 95% CI 70.8 to 98.6) to detect patients with structural abnormalities than FEV1 (36.4%, 95% CI 17.2 to 59.3). Conclusions We demonstrated that measuring LCI in patients with PCD is of clinical relevance; it was more frequently abnormal than FEV1, correlated well with CFCT and was more sensitive than FEV1 to detect patients with structural abnormalities.