Long-term course of lung clearance index among patients with cystic fibrosis

<b>Aim:</b> To investigate the role of age, different types of bronchial infection and pulmonary exacerbations upon lung function deterioration. <b>Methods:</b> 76 children and adults with CF (mean (range) age (years): 10.58 (1.75 to 23.75)) performed 1272 serial Multiple Breath Washout (MBW) measurements and 1047 spirometries over a 7-year period. 289 pulmonary Exacerbations (PEx) were recorded. Bacteria isolated from cough swabs/ sputum cultures were recorded. Patients were divided into 5 age-groups: &lt;5 years, 5 to 10 years, 11 to 15 years, 16 to 20 years and &gt;20 years. <b>Results:</b> Most lung function parameters showed significant progression with age (FRC, LCI, Scond, M1/M0, M2/M0, FEV1% predicted, FEF50% predicted). LCI deteriorated significantly among the older age groups: ΔLCI ((95% CI))= 0.38 (-0.24 to 1.01), p=0.228, 5-10 years; 1.14 (0.40 to 1.87), p=0.002, 11 – 15 years; 3.02 (2.11 to 3.94), p&lt;0.001, 16 to 20 years and 3.92 (2.87 to 4.97), p&lt;0.001, over 20 years. LCI deteriorated significantly during pulmonary exacerbations, ΔLCI ((95% CI)) 1.11 (0.83 to 1.39), p&lt;0.001. New Pseudomonas colonization caused a significant increase in LCI; ΔLCI 95% CI)) =0.35 (0.01 to 0.69), p=0.019. New Stenotrophomonas colonization caused a significant increase in LCI; ΔLCI 95% CI)) =1.19 (0.45 to 1.94), p&lt;0.001. <b>Conclusion:</b> The LCI demonstrates progression of lung disease and corresponds to changes in bacterial infections and pulmonary exacerbations among patients with CF. LCI may be a useful marker to track disease deterioration and may have a role in the routine clinical care of patients with CF.