Table 1.
Clinical characteristics of the study subjects
| Infrequent exacerbator | Frequent exacerbator* | P | |
|---|---|---|---|
| Number | 1328 | 126 | – |
| Age (years) | 46.27 ± 0.43 | 51.2 ± 1.16 | 1.05E−04 |
| Sex (male %) | 38.10% | 41.30% | 0.503 |
| Number of exacerbation in the first year | 0.25 ± 0.02 | 2.03 ± 0.11 | 1.21E−32 |
| Smoking status (non-smokers/ex-smokers/smokers, %) | 66.3/18.5/15.1% | 58.7%/22.2%/19.1% | 0.086 |
| Smoking amount (pack-year) | 5.86 ± 0.36 | 8.47 ± 1.46 | 0.084 |
| Atopy (%) | 48.80% | 39.70% | 0.05 |
| Duration of asthma (years) | 3.06 ± 0.2 | 5.95 ± 0.94 | 0.003 |
| Duration of follow-up (years) | 6.17 ± 0.12 | 7.29 ± 0.37 | 0.007 |
| Serum total IgE (IU/ml) | 356.3 ± 18.87 | 453.17 ± 62.05 | 0.131 |
| Body mass index (kg/m2) | 23.87 ± 0.12 | 23.96 ± 0.47 | 0.859 |
| Baseline FVC%, predicted | 83.02 ± 0.48 | 67.65 ± 1.4 | 1.45E−20 |
| Baseline FEV1%, predicted | 82.58 ± 0.6 | 58.4 ± 1.59 | 3.06E−30 |
| Baseline FEV1/FVC | 75.64 ± 0.34 | 64.81 ± 1.15 | 6.96E−20 |
| PC20, methacholine (mg/ml) (No. of study subjects) | 7.6 ± 0.29 (1,218) | 5.52 ± 0.83 (109) | 0.037 |
| Total ICS dosage used in the 1st year (Fluticasone eqv./day) | 211.36 ± 7.25 | 571.34 ± 43.82 | 3.16E−13 |
| Systemic prednisolone dose in the 1st year (mg/year) | 80.31 ± 9.55 | 564.14 ± 95.39 | 1.51E−06 |
Data are expressed as mean ± standard error
*Frequent exacerbator is defined as a subject experiencing an exacerbation 2 or more times in the first year of follow-up