Characteristics and spirometry values of participants in the study population, stratified by sex and by survey
| BCRDS | PSWON | HCRHS | BD-HUSK | Total | |
| Survey years | 1965–1970 | 1988–1990 | 1996–1997 | 1998–1999 | 1965–1999 |
| Birth years | 1894–1943 | 1944–1958 | 1914–1969 | 1925–1951# | 1894–1969 |
| Number of subjects | 5616 | 26 092 | 1993 | 2765 | 36 466 |
| Males | |||||
| Subjects | 2524 (45) | 26 092 (100) | 814 (41) | 1101 (40) | 30 531 (84) |
| Age years | 47.3±13.9 | 38.2±4.3 | 50.5±16.0 | 68.3±9.3 | 40.4±9.0 |
| Height cm | 174.6±6.6 | 178.8±6.3 | 177.5±6.9 | 175.7±6.6 | 178.3±6.5 |
| Smoking status | |||||
| Nonsmoker | 392 (16) | 8133 (31) | 267 (33) | 247 (23) | 9039 (30) |
| Ex-smoker | 461 (18) | 6395 (25) | 274 (34) | 640 (59) | 7770 (26) |
| Current smoker | 1671 (66) | 11 488 (44) | 273 (34) | 206 (19) | 13 638 (45) |
| Pack-years | 13.8±13.8 | 16.1±9.4 | 17.4±14.7 | 20.9±18.1 | 16.1±10.6 |
| Education | |||||
| <11 years | 982 (41) | 3476 (14) | 158 (20) | 229 (21) | 4845 (16) |
| 11–13 years | 1110 (47) | 15 450 (60) | 459 (57) | 550 (50) | 17 569 (59) |
| 14–20+ years | 292 (12) | 6785 (26) | 189 (23) | 311 (29) | 7577 (25) |
| FEV1, L | 3.88±1.05 | 4.28±0.62 | 3.68±0.95 | 2.90±0.74 | 4.18±0.74 |
| FEV1, z-score | 0.08±1.34 | −0.08±0.96 | −0.37±1.10 | −0.55±1.10 | −0.09±1.02 |
| FVC, L | 4.90±1.12 | 5.40±0.76 | 4.73±1.06 | 3.87±0.82 | 5.29±0.87 |
| FVC, z-score | 0.13±1.14 | 0.04±0.90 | −0.26±0.95 | −0.52±0.97 | 0.02±0.93 |
| Females | |||||
| Subjects | 3092 (55) | - | 1179 (59) | 1664 (60) | 5935 (16) |
| Age years | 48.3±14.0 | - | 50.6±15.0 | 60.8±12.2 | 52.3±14.8 |
| Height cm | 161.2±6.0 | - | 164.7±6.2 | 163.3±6.3 | 162.5±6.3 |
| Smoking status | |||||
| Nonsmoker | 1925 (62) | - | 533 (45) | 782 (48) | 3240 (55) |
| Ex-smoker | 144 (5) | - | 274 (23) | 454 (28) | 872 (15) |
| Current smoker | 1023 (33) | - | 372 (32) | 396 (24) | 1791 (30) |
| Pack-years | 6.6±6.2 | - | 11.9±10.1 | 13.3±11.0 | 9.9±9.4 |
| Education | |||||
| <11 years | 1717 (58) | - | 264 (23) | 438 (27) | 2419 (42) |
| 11–13 years | 1062 (36) | - | 649 (56) | 862 (53) | 2573 (44) |
| 14–20+ years | 198 (7) | - | 253 (22) | 339 (21) | 790 (14) |
| FEV1, L | 2.78±0.73 | - | 2.74±0.67 | 2.36±0.60 | 2.66±0.71 |
| FEV1, z-score | 0.10±1.29 | - | −0.20±1.04 | −0.37±1.06 | −0.09±1.20 |
| FVC, L | 3.38±0.79 | - | 3.43±0.76 | 3.00±0.69 | 3.28±0.78 |
| FVC, z-score | −0.02±1.13 | - | −0.16±0.93 | −0.38±0.92 | −0.15±1.05 |
Variables are presented as mean±sd or n (%) as appropriate. Z-scores calculated according to Global Lung Function Initiative (GLI-2012) equations. BCRDS: Bergen Chronic Respiratory Disease Survey; PSWON: Pneumoconiosis Survey of Western Norway; HCRHS: Hordaland County Respiratory Health Survey; BD-HUSK: Bronchodilatation Survey of the Hordaland Health Study; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity. #: two birth cohorts: 1925–1927 and 1950–1951.