Table 1.
Variables | Different definitions of outcomes
|
||||||
---|---|---|---|---|---|---|---|
Control population N=747 |
Airflow limitationa N=212 |
Chronic airflow limitation (GOLD)b N=105 |
Chronic airflow limitation (LLN)c N=100 |
COPDd N=50 |
Physician-diagnosed COPD/emphysemae N=25 |
Emphysemaf N=98 |
|
Age, years | 56.9 (4.3) | 58.1 (4.4) | 58.7 (4.2) | 58.1 (4.3) | 58.9 (4.0) | 57.3 (4.4) | 58.1 (4.5) |
Males | 371 (49.7%) | 96 (45.3%) | 60 (57.1%) | 57 (57.0%) | 31 (62%) | 14 (56%) | 55 (56.1%) |
BMI, kg/m2 | 27.3 (4.3) | 27.1 (5.0) | 27.2 (5.1) | 27.2 (5.4) | 27.1 (4.5) | 28.4 (6.4) | 26.2 (4.4) |
Never-smokers | 370 (49.5%) | 59 (27.8%) | 21 (20.0%) | 20 (20.0%) | 9 (18.0%) | 5 (20%) | 6 (6.0%) |
Former smokers | 282 (37.8%) | 94 (44.3%) | 43 (41.0%) | 41 (41.0%) | 22 (44.0%) | 10 (40%) | 34 (34.7%) |
Current smokers | 95 (12.7%) | 59 (27.8%) | 41 (39.1%) | 39 (39.0%) | 19 (38.0%) | 10 (40%) | 58 (59.2%) |
Pack-years | 7.4 (12.1) | 16.0 (19.3) | 21.6 (23.1) | 20.6 (2.3) | 23.4 (27.1) | 23.3 (17.8) | 27.8 (28.7) |
Occupational exposure to VGDF | 206 (27.6%) | 90 (42.5%) | 46 (43.8%) | 42 (42.0%) | 29 (58.0%) | 16 (64%) | 50 (51.0%) |
FEV1, % predicted | 103.5 (22.2) | 90.2 (23.7) | 83.1 (22.2) | 86.3 (25.0) | 80.4 (25.6) | 73.8 (19.9) | 87.2 (21.7) |
FVC, % predicted | 100.8 (23.4) | 101.7 (25.2) | 100.6 (24.4) | 104.7 (26.6) | 99.8 (26.9) | 84.5 (17.7) | 94.8 (22.1) |
FEV1/FVC, % | 80.7 (4.1) | 69.3 (7.0) | 64.3 (6.0) | 64.1 (6.1) | 62.4 (7.7) | 68.2 (12.4) | 71.9 (9.1) |
Notes: Categories overlap and are not mutually exclusive. SD is given in parentheses unless otherwise indicated.
Airflow limitation was defined as an FEV1/FVC ratio <0.7 before bronchodilation.
Chronic airflow limitation (GOLD) was defined as an FEV1/FVC ratio <0.7 after bronchodilation.
Chronic airflow limitation (LLN) was defined as an FEV1/FVC ratio after bronchodilation below the lower limit of the normal.
COPD was defined as chronic airflow limitation (GOLD) in combination with dyspnea, wheezing, or chronic bronchitis.
Physician-diagnosed COPD/emphysema was defined as an affirmative answer to “Have you ever had chronic obstructive pulmonary disease or emphysema diagnosed by a physician?”
Emphysema was categorized according to CT findings of at least mild emphysema in any zone.
Abbreviations: FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; CT, computed tomography; LLN, lower limit of normal.