Study demographics and sputum culture of PPM
| COPD | HS* | HV† | p Value‡ | |
|---|---|---|---|---|
| N | 18 | 8 | 11 | |
| Age (mean; range) | 60 (41–74) | 57 (39–70) | 50 (33–66) | 0.152‡ |
| Gender (female/male) | 4/14 | 5/3 | 5/6 | 0.117§ |
| FEV1 (mean; range; L) | 1.74 (0.84–2.26) | 3.10 (2.30–4.63) | 3.12 (2.10–3.90) | <0.0001‡ |
| FEV1% predicted (mean; range) | 57 (32–89) | 94 (71–118) | 98 (84–104) | <0.0001‡ |
| FEV1/FVC (mean; range) | 0.51 (0.32–0.69) | 0.79 (0.71–0.86) | 0.82 (0.74–0.92) | <0.0001‡ |
| Inhaled corticosteroids | 17/18 | 0 | 0 | <0.0001§ |
| Long-acting β-agonist | 17/18 | 0 | 0 | <0.0001§ |
| Positive PPM sputum culture, n (%) | ||||
| Streptococcus viridans group | 18 (100%) | 7 (88%) | 9 (82%) | |
| Streptococcus pneumoniae | 3 (17%) | 1 (13%) | 0 | |
| Streptococcus milleri group | 6 (33%) | 3 (38%) | 5 (45%) | |
| Haemophilus influenzae | 5 (28%) | 2 (20%) | 1 (10%) | |
| Aerococcus viridans | 1 (6%) | 0 | 0 | |
| Klebsiella pneumoniae | 1 (6%) | 0 | 0 | |
| Nesseria meningitidis | 1 (6%) | 0 | 0 | |
| Pseudomonas aeruginosa | 1 (6%) | 0 | 0 | |
| Staphylococcus aureus | 1 (6%) | 1 (13%) | 1 (10%) | |
*Single culture negative sample.
†Two culture negative samples.
‡Comparison between two or more groups by Kruskal–Wallis test.
§Comparison for categorical variables between the three cohorts by Pearson's χ2 test with Yates’ continuity correction.
HS, ‘healthy’ smokers; HV, healthy volunteers; PPM, potentially pathogenic microorganisms.