Distributions of age at spirometry and smoking status in relation to lung function
| Lung function* | ||||||
|---|---|---|---|---|---|---|
| Normal, n (%) | COPD | Restrictive lung disease, n (%) | Total, n (%) | |||
| Mild, n (%) | Moderate, n (%) | Severe, n (%) | ||||
| COPD, chronic obstructive pulmonary disease; FEV1, forced expiratory volume in 1 s; n, number of cohort members; VC, vital capacity. | ||||||
| *Normal: FEV1/VC ⩾70%, %FEV1 ⩾80%; mild COPD: FEV1/VC <70%, %FEV1 ⩾80%; moderate COPD: FEV1/VC <70%, %FEV1 = 50–79%; severe COPD: FEV1/VC <70%, %FEV <50%; restrictive lung disease: FEV1/VC ⩾70%, %FEV1 <80%. | ||||||
| Age at spirometry (years) | ||||||
| <20 | 19 559 (12) | 98 (3) | 177 (6) | 7 (2) | 1405 (18) | 21 246 (12) |
| 20–29 | 61 923 (38) | 557 (16) | 474 (16) | 22 (6) | 2079 (27) | 65 055 (37) |
| 30–39 | 37 744 (23) | 714 (20) | 378 (13) | 34 (9) | 1264 (16) | 40 134 (23) |
| ⩾40 | 43 240 (27) | 2139 (61) | 1926 (65) | 323 (84) | 2934 (38) | 50 562 (29) |
| Smoking status | ||||||
| Never smoked | 82 462 (51) | 964 (27) | 725 (25) | 65 (17) | 3373 (44) | 87 589 (49) |
| Former smoker | 20 433 (13) | 528 (15) | 350 (12) | 65 (17) | 808 (11) | 22 184 (13) |
| Current smoker | 59 571 (37) | 2016 (57) | 1880 (64) | 256 (66) | 3501 (46) | 67 224 (45) |
| Total | 162 466 (92) | 3508 (2) | 2955 (2) | 386 (<1) | 7682 (4) | 176 997 (100) |