Subject characteristics
| Period 1 (2014–2016) | |||
| Normal | PRISm | COPD | |
| Subjects, n | 1409 | 176 | 87 |
| Age (years)* | 56.1±9.5 | 60.1±9.2 | 56.3±9.2 |
| Male sex (%) | 805 (57.1%) | 112 (63.6%) | 59 (67.8%) |
| BMI (kg/m2)* | 23.6±3.4 | 23.9±4.6 | 22.7±2.9 |
| Current smoker, n (%) | 207 (14.7) | 42 (23.9) | 23 (26.4) |
| Former smoker, n (%) | 386 (27.4) | 53 (30.1) | 31 (35.6) |
| Never-smoker, n (%) | 816 (57.9) | 81 (46.0) | 33 (37.9) |
| FEV1 (litre)* | 2.70±0.62 | 2.03±0.44 | 2.31±0.67 |
| FVC (litre)* | 3.32±0.78 | 2.61±0.60 | 3.41±0.94 |
| FEV1/FVC (%)* | 81.4±5.0 | 78.4±5.6 | 67.6±3.6 |
| %FEV1 (%)* | 96.8±10.0 | 73.1±7.2 | 78.4±16.2 |
| %FVC (%)* | 95.0±10.3 | 74.0±8.4 | 92.2±16.8 |
| Drinking habit | |||
| Everyday | 454 (32.2) | 75 (42.6) | 34 (39.1) |
| Sometime | 594 (42.5) | 47 (26.7) | 34 (39.1) |
| Never | 361 (25.6) | 54 (30.7) | 19 (21.8) |
*Values are given as mean±SD or number (%).
BMI, body mass index; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; PRISm, preserved ratio impaired spirometry.