Table 1.
Patients' characteristics
| Classic asthma | Cough variant asthma | p-value | |
| n = 58 | n = 55 | ||
| Age (yr) | 44.4 ± 15.9 | 43.2 ± 16.5 | 0.71 |
| Male/Female (No) | 29/29 | 33/22 | 0.29 |
| Disease duration at diagnosis (yr) | 6.7 ± 10.0 | 2.8 ± 4.4 | 0.10 |
| Current smoking (Yes, %) | 19.0 | 5.2 | 0.029 |
| Atopic status* (Yes, %) | 71.4 | 67.9 | 0.69 |
| Blood eosinophils (number/μl) | 389 ± 247 | 310 ± 404 | 0.011 |
| FEV1 (% predicted) | 86.8 ± 19.2 | 92.1 ± 17.6 | 0.14 |
| FEV1/FVC (%) | 72.6 ± 11.3 | 81.8 ± 8.9 | < 0.0001 |
| Baseline Rrs (cm H2O/L/sec) | 4.3 ± 2.0 | 4.0 ± 3.2 | 0.040 |
| Log Dmin (units) | -0.20 ± 0.82 | 0.36 ± 0.60 | < 0.0001 |
| SRrs (cm H2O/L/sec/min) | 2.9 ± 3.2 | 2.1 ± 2.1 | 0.042 |
| Log C5 (μM) | 1.51 ± 0.79 (n = 18) | 1.17 ± 0.71 (n = 22) | 0.15 |
Values are given as the means ± SD.
*: measured in 56 patients with classic asthma and 53 patients with cough variant asthma. Patients were considered atopic when 1 or more specific IgE antibodies were positive for cat dander, dog dander, weed, grass pollen, mold, or house dust mite.
Abbreviation: Rrs, respiratory resistance. Dmin, cumulative dose of inhaled methacholine at the inflection point, where which respiratory resistance begins to increase. SRrs, slope of the methacholine dose-response curve for Rrs. C5, cough threshold, the lowest concentration of capsaicin that induces 5 or more cough.