Univariate relationship of each of the airway ratios and pulmonary function tests with age
| Age-related tested variable | Correlation (CI) | Regression | |||
| Regression coefficient | se | p-value | R² | ||
| FEV1 | −0.39 (−0.57– −0.19) | −4.92 | 1.11 | <0.001 | 0.18 |
| FVC | 0.03 (−0.19–0.25) | −0.07 | 0.27 | 0.794 | <0.01 |
| FEV1/FVC | −0.26 (−0.46–0.04) | −0.19 | 0.13 | 0.151 | 0.02 |
| MEF50% | −0.32 (−0.51– −0.10) | −1.83 | 0.62 | 0.004 | 0.08 |
| MEF25–75% | 0.05 (−0.18–0.27) | 0.07 | 0.67 | 0.911 | <0.01 |
| RV | 0.14 (−0.08–0.35) | 1.90 | 1.43 | 0.186 | 0.02 |
| FRC | −0.07 (−0.27–0.16) | −0,72 | 1,17 | 0.541 | <0.01 |
| TLC | −0.20 (−0.40– −0.16) | −1.69 | 0.69 | 0.016 | 0.06 |
| CV | −0.37 (−0.54– −0.16) | −3.17 | 0.95 | 0.001 | 0.11 |
| dN2 | 0.31 (0.10–0.50) | 1.05 | 0.35 | 0.003 | 0.09 |
| E/IMLD | 0.48 (0.29–0.64) | 119.01 | 24.83 | <0.001 | 0.20 |
| WT/WD B1 4th generation | 0.08 (−0.14–0.30) | 35.52 | 37.34 | 0.344 | <0.01 |
| WT/WA B1 4th generation | 0.10 (−0.12–0.32) | 41.30 | 27.66 | 0.139 | 0.02 |
| WT/WD B1 5th generation | 0.17 (−0.05–0.38) | 70.93 | 37.60 | 0.062 | 0.04 |
| WT/WA B1 5th generation | 0.10 (−0.13–0.31) | 24.75 | 15.76 | 0.119 | 0.02 |
| WT/WD B1 6th generation | 0.13 (−0.10–0.34) | 36.53 | 27.95 | 0.194 | 0.02 |
| WT/WA B1 6th generation | 0.04 (−0.18–0.26) | 3.45 | 7.38 | 0.641 | <0.01 |
| WT/WD B8 4th generation | 0.04 (−0.18–0.26) | 37.28 | 43.79 | 0.396 | <0.01 |
| WT/WA B8 4th generation | 0.01 (−0.21–0.23) | 21.89 | 29.97 | 0.467 | <0.01 |
| WT/WD B8 5th generation | −0.08 (−0.30–0.14) | −16.28 | 49.75 | 0.744 | <0.01 |
| WT/WA B8 5th generation | −0.01 (−0.23–0.21) | 8.04 | 22.97 | 0.727 | <0.01 |
| WT/WD B8 6th generation | 0.05 (−0.17–0.27) | 13.78 | 27.75 | 0.620 | <0.01 |
| WT/WA B8 6th generation | 0.19 (−0.03–0.39) | 10.96 | 8.25 | 0.187 | 0.02 |
| WT/WD B10 4th generation | 0.29 (0.07–0.48) | 101.31 | 29.78 | 0.001 | 0.12 |
| WT/WA B10 4th generation | 0.21 (−0.01–0.42) | 82.83 | 35.96 | 0.023 | 0.06 |
| WT/WD B10 5th generation | 0.23 (0.01–0.43) | 86.35 | 37.01 | 0.022 | 0.06 |
| WT/WA B10 5th generation | 0.18 (−0.05–0.39) | 69.49 | 33.29 | 0.039 | 0.05 |
| WT/WD B10 6th generation | 0.12 (−0.10–0.34) | 43.38 | 34.63 | 0.213 | 0.02 |
| WT/WA B10 6th generation | 0.04 (−0.19–0.26) | 6.05 | 23.15 | 0.794 | <0.01 |
| I−950 % | 0.08 (−0.12–0.29) | 0.01 | 0.01 | 0.429 | <0.01 |
| Pi10 | 0.06 (−0.17–0.28) | 0.49 | 0.40 | 0.227 | 0.01 |
FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; MEF50%: midexpiratory flow at 50% FVC; MEF25–74%: midexpiratory flow at 25–75% FVC; RV: residual volume; FRC: functional residual capacity; TLC: total lung capacity; CV: closing volume; dN2: phase III nitrogen slope; E/IMLD: expiratory/inspiratory ratio of mean lung density; WT: wall thickness; WD: wall diameter; B1: right apical bronchus; WA: wall area; B8: anterior basal bronchus; B10: posterior basal bronchus; I−950: proportion of low attenuation below the threshold of −950 HU in the whole inspiratory volume; Pi10: square root of WA for a standardised airway with an internal perimeter of 10 mm.