| Screening questionnaire responders only,n (%)(n = 883) | Subjects completing diagnostic modules, n (%)(n = 469) | p Value | |
| Male | 422/883 (47.8) | 271/469 (57.8) | <0.001 |
| Wheezing in the last 12 months | 208/879 (23.7) | 116/466 (24.9) | 0.62 |
| Cough without cold usually | 221/879 (25.1) | 125/466 (26.8) | 0.50 |
| Cough 3 months each year | 118/872 (13.5) | 83/457 (18.2) | 0.03 |
| Phlegm 3 months each year | 89/874 (10.2) | 60/459 (13.1) | 0.11 |
| Breathing trouble ever | 210/878 (23.9) | 124/467 (26.6) | 0.29 |
| Doctor-diagnosed chronic bronchitis | 78/881 (8.9) | 45/467 (9.6) | 0.64 |
| Doctor-diagnosed emphysema | 20/880 (2.3) | 8/464 (1.7) | 0.50 |
| Doctor-diagnosed asthma | 141/881 (16.0) | 94/466 (20.2) | 0.06 |
| Never smoker | 426 (49.8) | 210 (46.1) | 0.003 |
| Current smoker | 98 (11.5) | 32 (7.0) | |
| Former smoker | 331 (38.7) | 214 (46.9) | |
| Mean (SD) age (years) | 63.1 (8.3) | 61.6 (7.3) | <0.001 |
Age based on age at completion of screening questionnaire. The selection of study participants aged >50 years is based on age at time of pulmonary function tests, which were on average 1.1 years later. As a result, the ages presented in table 1 do not correspond with the ages stated in table 2. Likewise, smoking data presented in table 1 is based on the screening questionnaire and the smoking data presented in table 2 is based on the detailed written questionnaire completed by participants.