Baseline population characteristics
| ATS criteria | Total | ||
| Met | Not met | ||
| Subjects | 6 | 22 | 28 (100) |
| Males | 2 | 11 | 13 (46) |
| Females | 4 | 11 | 15 (54) |
| Mean age yrs | 73# | 63 | 65 |
| Dutch origin | 6 | 20 | 26 (93) |
| Pre-existing pulmonary disease | 6 | 20 | 26 (93) |
| COPD | 5 | 16 | 21 (75) |
| Lung cancer | 0 | 2 | 2 (7) |
| Prior tuberculosis | 2 | 1 | 3 (11) |
| Bronchiectasis | 2 | 3 | 5 (18) |
| Current smoker | 0 | 3 | 3 (11) |
| History of smoking | 3 | 11 | 14 (50) |
| Alcohol abuse | 0 | 1 | 1 (4) |
| HIV infection | 0 | 1 | 1 (4) |
| Haematological malignancy | 0 | 1 | 1 (4) |
| Otherwise impaired immunity¶ | 0 | 2 | 2 (7) |
Data are presented as n or n (%). ATS: American Thoracic Society; COPD: chronic obstructive pulmonary disease. ¶: methotrexate-associated pancytopenia and cystic fibrosis (each n = 1). #: significant difference, 95% confidence interval 3.0–18.0; p = 0.008.