Clinical characteristics of patients categorised based on the presence of NB
| NB | No NB | p Value | |
| Number of subjects | 43 | 225 | |
| Age (years), mean (range) | 61.0 (32.5, 78.9) | 55.3 (18.9, 85.9) | 0.028 |
| Sex, man, n (%) | 23 (53.5) | 94 (41.8) | 0.181 |
| Atopic, n (%) | 30 (71.4), n=42 | 159 (73.3), n=217 | 0.850 |
| Ex-smoker, n (%) | 18 (41.9) | 80 (35.6) | 0.490 |
| Pack years, median (q1,q3) | 6.2 (1.8, 25.0), n=18 | 8.0 (1.0, 26.0), n=77 | 0.961 |
| FEV1 % predicted, mean (SD) | 66.7 (14.4) | 81.3 (18.9) | <0.001 |
| FEV1/FVC (%), mean (SD) | 65.7 (10.1) | 71.0 (10.4) | 0.001 |
| ICS dose* (µg/day), median (q1,q3) | 1000 (800, 2000), n=35 | 1000 (800, 2000), n=171 | 0.705 |
| Sputum cell counts, median (q1,q3) | |||
| Total cell number (×106 cells/mL) | 11.2 (9.4, 19.8) | 3.1 (1.8, 4.5) | <0.001 |
| Viability (%) | 92.0 (87.1, 96.3) | 77.9 (66.7, 87.1) | <0.001 |
| Neutrophils (%) | 77.5 (70.2, 86.2) | 36.5 (23.5, 53.0) | <0.001 |
| Neutrophil (×104/mL) | 942.6 (666.6, 1586.9) | 103.2 (47.4, 201.3) | <0.001 |
| Eosinophils (%) | 1.0 (0.5, 3.0) | 1.5 (0.5, 6.7) | 0.305 |
| Eosinophil (×104/mL) | 13.4 (6.1, 46.6) | 4.0 (0.9, 19.3) | <0.001 |
| Macrophages (%) | 17.0 (10.7, 23.0) | 52.0 (36.2, 65.2) | <0.001 |
| Macrophage (×104/mL) | 218.7 (150.0, 302.9) | 145.8 (82.6, 243.8) | 0.004 |
| Lymphocytes (%) | 0.5 (0.2, 1.0) | 0.7 (0.2, 1.5) | 0.187 |
| Lymphocyte (×104/mL) | 5.5 (1.8, 16.5) | 1.8 (0.1, 4.7) | <0.001 |
| Columnar epithelial cells (%) | 0.2 (0.0, 1.0) | 1.7 (0.5, 4.9), n=224 | <0.001 |
| Columnar epithelial cells (×104/mL) | 4.7 (0, 12.1) | 4.3 (1.0, 11.9) n=224 | 0.943 |
| CXCL-8 (ng/mL), median (q1, q3) | 46.8 (16.8, 99.8), n=19 | 6.1 (2.3, 11.4), n=84 | <0.001 |
| Sputum culture performed, n (%) | 21 (48.8) | 116 (51.6) | 0.868 |
| Positive culture, n (%) | 11 (52.4) | 10 (8.6) | <0.001 |
| Purulent sputum, n (%) | 30 (69.8) | 46 (20.4) | <0.001 |
| Sputum colour, n (%) | |||
| 1 | 1 (2.3) | 56 (24.9) | <0.001 |
| 2 | 12 (27.9) | 123 (54.7) | 0.001 |
| 3 | 24 (55.8) | 43 (19.1) | <0.001 |
| 4 | 5 (11.6) | 3 (1.3) | 0.003 |
| 5 | 1 (2.3) | 0 (0.0) | 0.160 |
*ICS dose is calculated as beclomethasone equivalent dose, where 1 µg of beclomethasone=1 µg budesonide=0.5 µg fluticasone.
FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; ICS, inhaled corticosteroids; n, number of participants; NB, neutrophilic bronchitis; q, quartile.