TABLE I.
Characteristics of the study group and the Obstruction Phenotype subgroups
| All Subjects n=560 | None n=300 | Airflow Limitation n=181 | Air Trapping n=79 | Overall P-value | |
|---|---|---|---|---|---|
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| Age (yr) | 12.4 ± 3.0 | 12.6 ± 3.0 | 12.4 ± 3.0 | 11.9 ± 3.0 | 0.12 |
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| Sex (%M) | 58.4 | 58.0 | 60.2 | 55.7 | 0.78 |
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| Ethnic (%W/B/Mix) | 22.9/67.3/9.8 | 28.0/60.0/12.0 | 16.0/75.1/8.8 | 19.0/77.2/3.8 | 0.002 |
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| BMI | |||||
| Z-score | 1.05 ± 1.17 | 0.89 ± 1.16 | 1.28 ± 1.12 | 1.11 ± 1.24 | 0.002 |
| Z-BMI > 1.64 (%) | 37.7 | 31.0 | 48.1 | 39.2 | <0.001 |
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| Age at Diagnosis* (years) | 2 (1,5) | 3 (1,6) | 2 (1,4) | 2 (<1,3) | <0.001 |
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| Asthma Duration (years) | 9.0 ± 3.7 | 8.7 ± 3.8 | 9.2 ± 3.7 | 9.4 ± 3.6 | 0.14 |
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| Allergen Sensitizations | |||||
| Total Positive of 22* | 8 (3,14) | 7 (2,13) | 9 (4,15) | 12 (5,16) | <0.001 |
| Categories (%Positive): | |||||
| Foods | 49.5 | 44.7 | 55.2 | 54.4 | 0.051 |
| Mites | 51.4 | 45.7 | 54.7 | 65.8 | 0.004 |
| Molds | 45.2 | 36.7 | 50.3 | 65.8 | <0.001 |
| Pets | 56.8 | 52.3 | 58.6 | 69.6 | 0.019 |
| Pollens | 60.4 | 55.3 | 64.1 | 70.9 | 0.02 |
| Roaches | 44.3 | 42.0 | 43.6 | 54.4 | 0.14 |
| Rodents | 30.0 | 27.7 | 30.9 | 36.7 | 0.28 |
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| CASI Score (unmodified) | 4.1 ± 2.8 | 3.2 ± 2.4 | 4.7 ± 2.6 | 6.5 ± 2.9 | <0.001 |
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| FEV1 | |||||
| %Predicted | 93.5 ± 16.9 | 101.3 ± 13.2 | 88.6 ± 13.8 | 75.0 ± 17.4 | <0.001 |
| Z-score | −0.50 ± 1.32 | 0.11 ± 1.05 | −0.88 ± 1.08 | −1.93 ± 1.32 | <0.001 |
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| FVC | |||||
| %Predicted | 105.0 ± 15.0 | 105.8 ± 13.7 | 109.2 ± 13.7 | 92.6 ± 15.9 | |
| Z-score | 0.39 ± 1.21 | 0.46 ± 1.11 | 0.72 ± 1.10 | −0.62 ± 1.27 | |
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| FEV1/FVC | |||||
| ratio | 0.78 ± 0.09 | 0.84 ± 0.05 | 0.71 ± 0.06 | 0.71 ± 0.12 | |
| Z-score | −1.40 ± 1.13 | −0.64 ± 0.73 | −2.33 ± 0.53 | −2.14 ±1.30 | |
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| Δ %Prd FVC | 3.6 ± 6.7 | 1.6 ± 3.9 | 1.9 ± 4.8 | 14.9 ± 7.7 | |
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| Z-FEF25-75 | −1.32 ± 1.19 | −0.57 ± 0.83 | −2.06 ± 0.74 | −2.43 ± 1.25 | <0.001 |
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| FENO | |||||
| ppb* | 24 (13,46) | 19 (12,43) | 28 (13,48) | 29 (16,63) | 0.015 |
| >35 ppb (%) | 35.9 | 31.2 | 40.1 | 44.2 | 0.04 |
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| MeCh PC20 (mg/ml)* | 7.5 (1.9,≥25) | 18.1 (3.1,≥25) | 3.5 (1.3,14.7) | 1.5 (0.6,4.9) | <0.001 |
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| Total IgE (kU/L)* | 249 (82,764) | 193 (57,622) | 252 (103,879) | 506 (152,1398) | <0.001 |
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| Blood EOS (cells/μL)* | 300 (160,448) | 230 (110,400) | 300 (185,485) | 400 (200,600) | 0.001 |
Except as noted, continuous variables are expressed as mean ± SD, with overall P-value obtained from analysis of variance among the 3 obstruction phenotype subgroups. Categorical variables are expressed as percentages, and the P-value determined with a Chi square test.
*
Expressed as median (interquartile range), and P-value obtained with the Kruskal-Wallis test.
All variables were measured at the 12 month study visit, except blood eosinophils, allergen sensitizations, and serum IgE were measured at the initial visit, and MeCh PC20 was measured at the 8 or 10 month visit.