Demographic characteristics of patients with a successful diagnostic procedure compared to patients without aetiology
| Parameter | No aetiology | Probable or definite aetiology | p-value | 95% CI of the difference |
| Patients n | 82/204 (40) | 122/204 (60) | ||
| Age yrs mean±sd | 71±18 | 66±16 | 0.019 | 1.0–0.4 |
| Sex male | 50/82 (61) | 92/122 (75) | 0.028 | 0.9–21.7 |
| Current smokers | 19/82 (23) | 44/122 (36) | 0.051 | 0.5–25.5 |
| Alcohol abuse | 8/82 (10) | 25/122 (21) | 0.041 | 1.3–20.7 |
| Nursing home admission | 4/81 (5) | 4/121 (3) | 0.560 | −3.6–7.6 |
| Probable aspiration | 9/79 (11) | 5/111 (5) | 0.073 | −2.0–14.0 |
| H2-blockers | 7/81 (9) | 7/120 (6) | 0.443 | −4.5–10.5 |
| Comorbidity present | 65/82 (79) | 122/122 (68) | 0.078 | −1-1–23.1 |
| Type of comorbidity | ||||
| Cardiac | 22/82 (27) | 12/122 (10) | 0.001 | 6.0–28.0 |
| Pulmonary | 44/82 (54) | 67/122 (55) | 0.859 | −12.9–4.9 |
| Chronic Bronchitis | 10/82 (12) | 13/122 (11) | 0.733 | −8.0–0.0 |
| COPD | 29/82 (35) | 38/122 (31) | 0.529 | −9.2–7.2 |
| Bronchiectasis | 0/82 (0) | 3/122 (3) | 0.211# | 0.0–6.0 |
| Asthma | 0/82 (0) | 5/122 (4) | 0.073# | 0.7–7.5 |
| Others | 5/82 (6) | 8/122 (7) | 0.918 | −5.8–7.8 |
| Renal | 10/82 (12) | 4/122 (3) | 0.014 | 1.3–16.7 |
| Hepatic | 2/81 (3) | 10/122 (8) | 0.090 | −1.1–1.1 |
| CNS | 12/82 (15) | 15/122 (12) | 0.888 | −6.6–12.6 |
| Diabetes mellitus | 14/82 (17) | 17/122 (14) | 0.540 | −7.2–13.2 |
| Neoplastic | 5/82 (6) | 11/122 (9) | 0.461 | −4.2–10.2 |
Data are presented as n/total n (%), unless otherwise stated
CI: confidence interval
COPD: chronic obstructive pulmonary disease
CNS central nervous system
# Fisher's exact test
The exact numbers are given for each parameter, since information was not available for all patients