Table 1. Characteristics of the study population (N=131)a.
| All patients N=131 | No asthma N= 93 (71%) | Asthma b N= 38 (29%) | P Value | |
|---|---|---|---|---|
| Characteristic | ||||
| Age, years (mean, SD) | 11.2 (3.6) | 11.1 (3.5) | 11.3 (3.8) | 0.81 |
| Total follow up time from birth, years (mean, SD) | 16.2 (3.9) | 16.2 (3.7) | 16.4 (4.2) | 0.73 |
| Total follow-up time after eNO was obtained, years (mean, SD) | 5.1 (1.1) | 5.0 (1.1) | 5.1 (1.3) | 0.65 |
| Male (%) | 55.0 | 49.5 | 68.4 | 0.048 |
| Hemoglobin, g/dl (mean, SD) | 8.4 (1.3) | 8.5 (1.3) | 8.2 (1.1) | 0.24 |
| White blood cell count, 109/L (mean, SD) | 11.6 (3.7) | 11.3 (3.9) | 12.3 (3.0) | 0.15 |
| FeNO, ppb (median, IQR) | 9.0 (7.6) | 8.9 (7.3) | 9.9 (9.0) | 0.60d |
| FeNO ≥ 25 ppb (%) | 8.4% | 7.5 | 10.5 | 0.73 |
| IgE, IU/ml (median, IQR) (n=127) | 46.6 (133.3) | 47.6 (121.6) | 63.6 (152.8) | 0.77d |
| Eosinophils, total count (median, IQR) | 354.0 (492.0) | 320.0 (451.2) | 456.0 (606.2) | 0.35d |
| Had 2 or more positive skin tests (%, n=121) | 28.9% | 20.5% | 47.4% | 0.002 |
| FVC, % predicted (mean, SD) | 93.5 (14.1) | 93.8 (13.7) | 92.8 (15.0) | 0.71 |
| FEV1, % predicted (mean, SD) | 88.8 (13.3) | 89.8 (13.2) | 86.4 (13.5) | 0.19 |
| FEV1/FVC (mean, SD) | 0.85 (.07) | 0.85 (0.07) | 0.83 (0.08) | 0.13 |
| FEV1/FVC, % predicted (mean, SD) | 94.9 (7.7) | 95.6 (7.0) | 93.3 (9.3) | 0.14 |
| FEV1/FVC < LLN (%) | 19.8 | 15.1 | 31.6 | 0.03 |
| Percent with bronchodilator response ≥12%c | 16.8 | 11.8 | 28.9 | 0.02 |
| Retrospective rate of pain episodes per year (median, IQR) | 0.3 (0.6) | 0.3 (0.7) | 0.3 (0.6) | 0.88d |
| Retrospective rate of ACS episodes per year (median, IQR) | 0.1 (0.3) | 0.1 (0.2) | 0.2 (0.3) | 0.04d |
| Prospective rate of pain episodes per year (median, IQR) | 0.6 (1.3) | 0.5 (1.3) | 0.6 (1.3) | 0.80d |
| Prospective rate of ACS episodes per year (median, IQR) | 0.2 (0.3) | 0.0 (0.3) | 0.2 (0.5) | <0.001d |
| On hydroxyurea at the time FeNO was obtained (%) | 11.5 | 9.7 | 15.8 | 0.37 |
| On inhaled corticosteroids at the time FeNO was obtained | 21% | 2% | 66% | <0.001 |
| PC20 ≤ 8.0 (%) (n=66) | 63.6 | 65.1 | 60.9 | 0.73 |
Abbreviations: SD=standard deviation; FeNO=exhaled nitric oxide; ppb=parts per billion; IQR=interquartile range; FVC=forced vital capacity; FEV1=forced expiratory volume in 1 second; ACS=acute chest syndrome
a
Means and SD are presented for normally distributed variables, Medians and IQR's are presented for non-normally distributed variables
b
Participants were classified as having asthma if had ever been a physician diagnosis of asthma and current use of an asthma medication at the time of the FeNO measurement.[7]
c
(Post FEV1-Pre FEV1)/Pre-FEV1≥0.12
d
Mann-Whitney U test