Spirometry results, smoking status, reported chronic respiratory diseases and symptoms among participants aged >40 years compared to an age- and gender-matched reference group from the general population
| Participants (n=128), | Controls (n=384), | ||
| Spirometry | Mean±SD | Mean±SD | p (t test) |
| FEV1 % predicted* | 94±15 | 90±17 | 0.003 |
| FVC % predicted | 98±15 | 95±14 | 0.105 |
| FEV1/FVC % predicted | 96±9 | 93±11 | 0.004 |
| ∆FEV1 (% increase after bronchodilation) | 3±7 | 4±7 | <0.000 |
| COPD | n (%) | n (%) | p (χ2 test) |
| GOLD stage I or higher† | 25 (20) | 77 (20) | 1 |
| GOLD stage II or higher | 15 (12) | 42 (11) | 0.87 |
| Self-reported | |||
| Smoking | |||
| Current | 19 (15) | 154 (40) | 0.00* |
| Former | 31 (24) | 159 (41) | |
| Never | 76 (59) | 71 (18) | |
| Ever asthma | 21 (20) | 74 (19) | 0.30 |
| Ever COPD | 3 (2) | 6 (2) | 0.70 |
| Chronic phlegm‡ | 11 (8) | 38 (10) | 0.61 |
| Chronic cough‡ | 11 (8) | 43 (11) | 0.33 |
↵* Predicted values from the National Health and Nutrition Examination Survey cohort.
↵† GOLD stage I COPD, FEV1/FEV1 <0.7; GOLD stage II COPD, FEV1/FEV1 <0.7 and FEV1 <80% predicted.
↵‡ History of cough or phlegm 3 months or more every year.
∆FEV1, increase in FEV1 % predicted after use of bronchodilation; COPD, chronic obstructive pulmonary disease; FEV1, forced expiratory volume in one second; FVC, forced vital capacity.