Subject demographics and characteristics
| Normal control | Smoker normal FOT | Smoker abnormal FOT | |
| Subjects | 7 | 7 | 9 |
| Demographic data | |||
| Age years | 35 (28–49) | 61 (58–68)* | 63 (60–67)* |
| Male | 6 (86) | 6 (86) | 5 (56) |
| Caucasian | 5 (71) | 7 (100) | 9 (100) |
| BMI kg·m−2 | 28 (21–30) | 31 (25–33) | 27 (25–29) |
| Tobacco use | |||
| Current smoker | 0 (0) | 1 (14) | 3 (33) |
| Duration pack-years | 0 (0) | 31 (15–46)* | 46 (31–49)* |
| Symptoms | |||
| Any symptom | 0 (0) | 1 (14) | 2 (22) |
| Exertional dyspnoea | 0 (0) | 1 (14) | 1 (11) |
| Wheeze | 0 (0) | 1 (14) | 1 (11) |
| Cough | 0 (0) | 0 (0) | 2 (22) |
| Sputum production | 0 (0) | 0 (0) | 1 (11) |
Data are presented as n, median (interquartile range) or n (%). FOT: forced oscillation technique; BMI: body mass index. *: p-value <0.05, compared with normal control group (Kruskal–Wallis).