Table V.
Clinical characteristics of asthma phenotypes
| Asthma cluster 1: Severe air trapping, bronchial wall thickening, and bronchial lumen dilatation (n = 11) | Asthma cluster 2: Moderate air trapping (n = 34) | Asthma cluster 3: Severe air trapping and bronchial lumen narrowing (n = 17) | Significance (P value) | |
|---|---|---|---|---|
| Age (y) | 51.9 (9.6) | 49.3 (13.1) | 54.7 (10.4) | .3 |
| Sex (M/F) | 4:7 | 17:17 | 9:8 | .7 |
| BMI (kg/m2) | 25.0 (3.4) | 28.3 (5.5) | 31.5 (7.3) | .02§ |
| BSA (m2) | 1.9 (0.2) | 1.9 (0.2) | 2.0 (0.3) | .3 |
| Patients with severe asthma (%) | 81.8 | 58.8 | 94.1 | .02 |
| Disease duration (y) | 26.3 (16.1) | 26.4 (16.1) | 27.2 (17.5) | 1.0 |
| Smoking status (%) | ||||
| Never | 60 | 74 | 82 | .6 |
| Exsmoker | 40 | 23 | 18 | |
| Current smoker | 0 | 3 | 0 | |
| Smoking history >10 pack years (%) | 8 | 3 | 13 | .5 |
| Atopy (%) | 73 | 69 | 69 | 1.0 |
| Aspergillus species sensitization (%) | 36 | 17 | 29 | .4 |
| Severe exacerbations/y† | 2.5 (1-4.25) | 1.5 (0-5.0) | 2 (1.0-6.5) | .6 |
| Modified ACQ score (symptoms only) | 2.1 (0.9) | 2.0 (1.5) | 2.8 (1.3) | .1 |
| AQLQ score | 4.9 (1.0) | 5.0 (1.4) | 4.1 (1.1) | .09 |
| Prebronchodilator FEV1 (% predicted) | 58.0 (17.3) | 80.7 (19.9) | 64.0 (19.6) | .001‡‖ |
| Prebronchodilator FEV1/FVC ratio (%) | 64.8 (12.9) | 71.1 (9.7) | 67.0 (13.5) | .2 |
| Postbronchodilator FEV1 (% predicted) | 63.8 (17.7) | 83.8 (20.0) | 70.6 (16.6) | .005‡‖ |
| Postbronchodilator FEV1/FVC ratio (%) | 67.0 (13.2) | 72.8 (10.4) | 67.2 (10.7) | .2 |
| Bronchodilator response (%) | 11.1 (11.8) | 4.4 (7.2) | 13.9 (20.8) | .04‖ |
| Midexpiratory flow (L/s) | 2.0 (1.4) | 2.1 (0.9) | 1.9 (1.0) | .8 |
| Vital capacity (L) | 3.5 (1.0) | 4.0 (1.0) | 3.6 (1.1) | .4 |
| Functional residual capacity (L) | 3.6 (1.2) | 2.7 (0.8) | 2.7 (1.1) | .06 |
| RV (L) | 2.7 (0.9) | 1.7 (0.7) | 2.1 (1.0) | .02‡ |
| TLC (L) | 6.2 (1.4) | 5.7 (1.4) | 5.8 (1.9) | .8 |
| RV/TLC (%) | 43.5 (11.2) | 29.1 (6.3) | 35.5 (10.6) | .001‡ |
| Methacholine PC20 (mg/mL)∗ | 1.5 (0.1-16.4) | 3.7 (1.2-11.5) | 0.7 (0.07-5.6) | .2 |
| Feno (ppb)∗ | 37.5 (20.0-70.2) | 30.5 (22.6-41.3) | 38.8 (24.5-61.4) | .6 |
| Total IgE (kU/L)∗ | 227.2 (81.3-634.9) | 139.2 (97.3-199.1) | 217.9 (110.0-432.4) | .3 |
| Inhaled CS (%) | 100 | 91 | 100 | .3 |
| Inhaled CS dose BDP (μg/24 h)† | 2000 (1450-2000) | 2000 (1000-2000) | 2000 (1500-2000) | .2 |
| LABA (%) | 100 | 77 | 100 | .03 |
| Oral CS (%) | 60 | 41 | 53 | .5 |
| Montelukast (%) | 10 | 24 | 29 | .5 |
| Theophylline (%) | 40 | 29 | 35 | .8 |
| Sputum eosinophils (%)∗ | 2.8 (0.9-8.4) | 3.3 (1.6-6.7) | 5.7 (1.5-20.6) | .6 |
| Sputum total neutrophils × 106 (cells/g) | 2.0 (1.8) | 2.4 (3.6) | 2.4 (2.1) | .9 |
Data are expressed as means (SDs). Pearson χ2 and Fisher exact tests were used to compare ratios. Beclomethasone dipropionate equivalents are as follows: fluticasone, 2:1; budesonide, 1.25:1; mometasone, 1.25:1; QVAR, 2:1; and ciclesonide, 2.5:1.
ACQ, Asthma Control Questionnaire; AQLQ, Asthma Quality of Life Questionnaire; BDP, beclomethasone dipropionate; BMI, body mass index; CS, corticosteroid; Feno, fraction of exhaled nitric oxide; FVC, forced vital capacity; LABA, long-acting β2-agonist.
Geometric mean (95% CI).
Median (interquartile range).
Intergroup comparisons
For parametric data, 1-way ANOVA with the Tukey test to compare all pairs of columns: ‡P < .05, asthma cluster 1 versus asthma cluster 2; §P < .05, asthma cluster 1 versus asthma cluster 3; and ‖P < .05, asthma cluster 2 versus asthma cluster 3.
For nonparametric data, Kruskal-Wallis test with the Dunn multiple comparison test to compare all pairs of columns: ‡P < .05, asthma cluster 1 versus asthma cluster 2; §P < .05, asthma cluster 1 versus asthma cluster 3; and ‖P < .05, asthma cluster 2 versus asthma cluster 3.