Intraclass correlation coefficients for within and between visit measures of the lung clearance index
| Mean±sd V1 | Mean±sd V2 | Within visit ICC 20 min | Mean±sd V3 (between visit) | Between visit ICC 8 weeks | |
| FEV1 | 1.36±0.47 | 1.42±0.46 | 1.35±0.43 | 0.92 | |
| FEV1 % | 51.45±14.86 | 52.94±16.71 | 52.94±16.71 | 0.92 | |
| FEF25–75 | 0.58±0.36 | 0.62±0.26 | 0.62±0.26 | 0.64 | |
| FVC L | 2.58±0.63 | 2.86±0.73 | 2.57±0.55 | 0.74 | |
| LCI1/40th | 11.24±2.25 | 11.11±1.90 | 0.92 | 11.42±2.03 | 0.88 |
| FRC1/40th L | 3.51±1.11 | 3.19±0.93 | 0.96 | 3.50±0.89 | 0.92 |
| Scond | 0.06±0.11 | 0.06±0.15 | 0.94 | 0.04±0.03 | 0.52 |
| Sacin | 0.784±0.46 | 0.84±0.59 | 0.95 | 0.698±0.40 | 0.80 |
| LCIds | 1.29±0.36 | 1.27±0.21 | 0.47 | 1.43±0.38 | 0.05 |
| LCIvent | 1.54±0.31 | 1.50±0.25 | 0.80 | 1.51±0.20 | 0.10 |
| LCI1/20th | 8.59±1.43 | 8.40±1.27 | 0.96 | 8.53±1.18 | 0.80 |
| FRC1/20th L | 3.40±1.05 | 3.55±1.01 | 0.90 | 3.38±1.01 | 0.91 |
n=19. Intraclass correlation coefficient (ICC) measured by Pearson's correlation coefficient. FEV1: forced expiratory volume in 1 s; FEF25–75: forced expiratory flow at at 25–75% of FVC; FVC: forced vital capacity; LCI: lung clearance index; FRC: functional residual capacity; Scond: convection-dependent ventilation heterogeneity, Sacin: diffusion-convection-dependent ventilation heterogeneity. 1/40th=FRC or LCI calculated at traditional stopping point. 1/20th=FRC or LCI calculated at truncated stopping point of 1/20th of the end tidal wash-in concentration over three consecutive breaths.