Table 1.
Characteristics of the Patients at Baseline.*
| Characteristic | Low Eosinophil Level (N = 221) |
High Eosinophil Level (N = 74) |
|---|---|---|
| Demographic features | ||
| Age — yr | 31.2+13.8 | 31.1+14.2 |
| Male sex — no. (%) | 76 (34) | 35 (47) |
| Asthma history | ||
| Median age at diagnosis (IQR) — yr | 8.0 (3.0–15.0) | 7.0 (3.0–14.0) |
| Duration of asthma — yr | 19.2+10.9 | 20.0+12.2 |
| One or more asthma episodes requiring emergency care or unscheduled office visit in previous yr — no. (%) | 52 (24) | 17 (23) |
| One or more courses of systemic glucocorticoids in previous yr — no. (%) | 41 (19) | 14 (19) |
| Clinical and spirometric features | ||
| Body-mass index† | 29.1+7.8 | 26.5+5.7 |
| Predicted FEV1 — % | 92.7+12.4 | 89.5+10.8 |
| Ratio of FEV1 to FVC | 0.77+0.08 | 0.75+0.08 |
| Geometric mean PC20 (±CV) — mg/ml‡ | 2.42+1.28 | 1.24+1.27 |
| Bronchodilator response (4 puffs) — % change | 9.6+7.1 | 12.7+8.5 |
| Median fraction of exhaled nitric oxide (IQR) — ppb | 21.5 (14.0–35.5) | 55.5 (35.0–81.0) |
| Median blood eosinophil level (IQR) — % | 2.6 (1.1–4.0) | 4.8 (3.9–7.0) |
| Median periostin level (IQR) — ng/ml | 51.7 (43.3–63.6) | 56.3 (49.3–75.2) |
| Median score on Asthma Control Test (IQR)§ | 21.0 (20.0–23.0) | 21.0 (19.0–23.0) |
| Patients with eczema or atopic dermatitis — no. (%) | 67 (30) | 27 (36) |
| Patients with ≥1 positive allergen test — no./total no. (%) | 172/216 (80) | 70/72 (97) |
*
Plus-minus values are means ±SD unless otherwise noted. CV denotes coefficient of variation, FEV1 forced expiratory volume in 1 second, FVC forced vital capacity, and IQR interquartile range.
†
The body-mass index is the weight in kilograms divided by the square of the height in meters.
‡
PC20 denotes the provocative concentration of inhaled methacholine that results in a 20% reduction in the FEV1.
§
The score on the Asthma Control Test ranges from 5 (uncontrolled) to 25 (well controlled), with a minimally important difference of 3.