Demographic characteristics of patients with asthma and healthy volunteers (Belfast and Leicester cohorts combined)
| Healthy volunteers (n=22) | Patients with mild to moderate asthma (n=30) | Patients with severe asthma (n=31) | p Value* | |
| Age (years), median (IQR) | 30 (22–45) | 29 (24–39) | 48 (38–54)† | <0.0001 |
| Sex, men/women (n) | 10/12 | 14/16 | 22/9 | 0.09 |
| Duration of asthma (years), mean±SD | N/A | 12±10 | 22±15‡ | 0.007 |
| Atopy (n) | 11 | 21 | 23 | 0.16 |
| FEV1 (litre/min), mean±SD | 3.67±0.78 | 3.32±0.77 | 2.48±0.67§ | <0.0001 |
| FEV1 (% predicted), mean±SD | 102.8±11.9 | 93.5±16.0 | 75.9±16.9¶ | <0.0001 |
| FEV1/ FVC, mean±SD | 82.1±9.8 | 75.9±10.6 | 64.6±11.1** | <0.0001 |
| Inhaled steroid (n) | 0 | 19 | 31 | <0.0001 |
| BDP equivalent (μg), median (IQR) | 0 | 400 (0–800) | 1600 (1200–1600)†† | |
| Maintenance systemic steroids (n) | 0 | 0 | 15 (median dose prednisolone 5 mg (0–10 mg) plus 1 subject maintenance intramuscular triamcinolone) | |
| Theophylline (n) | 0 | 1 | 17 | <0.0001 |
| Long-acting β2-agonists (n) | 0 | 14 | 31 | <0.0001 |
| Prior smoking history (pack years) (n, median range) | 1 (4) | 5 (1, 1–10) | 13 (2.5, 1–20) | 0.004 |
| Eosinophils (109/litre), median (IQR) | 0.1 (0.07–0.21) | 0.26 (0.14–0.45)‡‡ | 0.49 (0.25–0.74)§§ | <0.0001 |
| IgE (kU/litre), geometric mean (95% confidence interval) | 24.6 (13.3 to 45.8) | 159.8 (89.8 to 284.6)¶¶ | 238.5 (136.2 to 417.5)*** | <0.0001 |
Comparison with the healthy volunteer group: †p<0.001, §p<0.001, ¶p<0.001, **p<0.001, §§p<0.001, ‡‡p<0.05, ¶¶p<0.001. Comparison with patients with mild to moderate asthma: †p<0.001, ‡p=0.007, §p<0.001, ¶p<0.001, **p<0.001, ††p<0.0001, §§p<0.05, ***p<0.001.
↵* Calculated by analysis of variance (ANOVA) with Bonferroni's multiple comparisons test (parametric) or Kruskal–Wallis with Dunn's multiple comparison test (non-parametric) or t-test when only asthma groups compared or χ2 for categorical variables (sex, atopy, theophylline, long-acting β2 agonists, smoking history).
BDP, beclometasone dipropionate; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity.