Lung clearance index in alpha-1-antitrypsin deficiency - A follow up

Abstract

We have shown that the Lung Clearance Index (LCI) derived from Multiple Breath Nitrogen Washout (MBW N2 ) is more sensitive for detecting pulmonary changes than spirometry, with an abnormal LCI in almost 40% of patients with a normal FEV 1 . The aim of this follow up study was to assess the natural course of lung function in A1ATD using MBW N2 and spirometry. 117 patients with a normal FEV 1 at baseline were identified from our A1ATD cohort. MBW N2 and comparative spirometry using the EasyOne Pro LAB TM (ndd Switzerland) were performed according to international standards. 66/117 (6,7-72,7 years) eligible subjects participated. Mean (SD) interval between the two tests was 1,7 (0,4) years. At baseline and follow up, mean (SD) LCI was 7,3 (1,18) and 7,3 (1,46) respectively (95% ci -0,161; 0,228, p= 0,730 ); mean FEV 1 -z (SD) was -0,20 (0,73) and -0,28 (0,97) (95% ci -0,062;0,222, p= 0,265) with no significant change between the test occasions in patients with either normal or abnormal LCI at baseline. N=7 patients changed from a normal LCI at baseline to an LCI above the upper limit of normal, whereas n=5 other patients changed from normal FEV 1 -z at baseline to FEV 1 -z below the lower limit of normal. Longitudinal measurement of LCI in A1ATD is feasible. The LCI appears to be a robust parameter for assessing A1ATD related pulmonary changes. Our data suggest that even when early changes are detected by MBW N2 , progress is slow so that there may be time for effective prevention and/or therapeutic intervention. Further follow up is necessary to understand early lung disease in A1ATD in relation to different lung function parameters. This project is supported by Deutsche Lungenstiftung and Grifols.