TABLE III.
Comparison of study design and results from independent asthma phenotype clustering analyses
| CAMP (current study) | SARP childhood study | SARP adult study | |
|---|---|---|---|
| Sample size | 1041 | 161 | 726 |
| Age distribution (y) | 5–13 | 6–17 | 12–80 |
| Percentage non-Hispanic white | 68 | 39 | 64 |
| Inclusion criteria | Dx, AHR, BDR No active symptoms |
Dx, AHR, BDR No active symptoms |
Dx, nonsmokers |
| ICS at time of evaluation | No | Yes × 6 mo | Yes |
| Spectrum of severity at enrollment | Mild to moderate | Mild to severe | Mild to severe |
| Variables included in model | 18 | 12 | 34 |
| No. of clusters | 5 | 4 | 5 |
| AOE cluster subtypes | |||
| 1. LLL | Cluster 1 (28.8%) | Cluster 1 (29.8%) | Cluster 1 (15.2%) |
| Descriptor | Mild asthma with a low atopic burden | Late onset, normal lung function | Young female subjects with atopic asthma and normal lung function |
| Age of asthma onset (y) | 3.52 | 6.08 | |
| Total serum IgE (kU/L) | 234 | 105 | 141 |
| AD | 0% | 50% | |
| Pre-BD FEV1/FVC ratio | 0.82 ± 0.8 | 0.82 ± 0.11 | 0.78 ± 0.1 |
| Exacerbation rate (rank) | Lowest | Lowest | Lowest |
| 2. HLL | Cluster 2 (19.4%) | Cluster 2 (32.3%) | Cluster 2 (44.2%) |
| Descriptor | Atopic with preserved lung function | Early onset, atopic, normal lung function | Older female subjects with atopic asthma and normal lung function |
| Age of asthma onset (y) | 3.09 | 2.5 | |
| Total serum IgE (kU/L) | 524 | 405 | 125 |
| AD | 100% | 56% | |
| Pre-BD FEV1/FVC ratio | 0.81 ± 0.8 | 0.79 ± 0.09 | 0.74 ± 0.1 |
| Exacerbation rate (rank) | Second lowest | Second lowest | Second lowest |
| 3. HHM | Cluster 3 (20.9%) | Cluster 3 (19.9%) | Cluster 4 (16.5%) |
| Descriptor | High obstruction, severe AHR | Early onset, atopic, mild airflow limitation | Childhood-onset atopic asthma, severe obstruction, high BDR |
| Age of asthma onset (y) | 3.66 | 1.2 | |
| Total serum IgE (kU/L) | 616 | 216 | 132 |
| AD | 0.1% | 47% | |
| Pre-BD FEV1/FVC ratio | 0.78 ± 0.8 | 0.72 ± 0.10 | 0.64 ± 0.1 |
| Exacerbation rate (rank) | Third lowest | Third lowest | Third lowest |
| 4. MHH | Cluster 4 (21.6%) | Not represented | Cluster 5 (16.0%) |
| Descriptor | Low atopy, high obstruction, high exacerbation | Childhood-onset atopic asthma, severe obstruction, low BDR | |
| Age of asthma onset (y) | 2.21 | ||
| Total serum IgE (kU/L) | 436 | 98 | |
| AD | 0% | ||
| Pre-BD FEV1/FVC ratio | 0.78 ± 0.08 | 0.57 ± 0.1 | |
| Exacerbation rate (rank) | Second highest | Second highest | |
| 5. HHH | Cluster 5 (9.2%) | Cluster 4 (18.0%) | Cluster 3 (8.13%) |
| Descriptor | Exacerbation | Early onset, atopic, advanced airflow limitation | Older women, high BMI, low atopy, low BDR |
| Age of asthma onset (y) | 2.68 | 1.6 | |
| Total serum IgE (kU/L) | 645 | 361 | 54 |
| AD | 97.9% | 72% | |
| Pre-BD FEV1/FVC ratio | 0.79 ± 0.09 | 0.73 ± 0.10 | 0.74 ± 0.1 |
| Exacerbation rate (rank) | Highest | Highest | Highest |
AHR, Airway hyperresponsiveness; BD, bronchodilator; BDR, bronchodilator response; ICS, inhaled corticosteroid; Dx, diagnosis.