Table 1.
The Severe Asthma Research Program adult cluster analysis: clinical characteristics of subject groups
| Spectrum of Early-Onset Allergic Asthma |
Spectrum of Late-Onset Adult Asthma |
||||
|---|---|---|---|---|---|
| |
Mild |
Moderate |
Severe |
Fixed Airflow |
Very Late Onset, Obese |
| Cluster 1 | Cluster 2 | Cluster 4 | Cluster 5 | Cluster 3 | |
| % of all subjects in group | 15 | 44 | 17 | 16 | 8 |
| Severe, % | <25 |
70–80 |
50 | ||
| Current age, decades | 20s | 20–30s | 30–40s | 40–50s | 40–50s |
| African American, % | 30 | 30 | 30 | 20 | 20 |
| Female sex, % | 80 | 67 | 53 | 63 | 71 |
| Obese with BMI > 30, % | 24 | 31 | 44 | >50 |
|
| Asthma onset | |||||
| Age, median (IQR), yr* | 9 (5–17) | 7 (2–18) | 4 (1–13) | 20 (5–32) | 41 (33–49) |
| Relevant life events | School aged | Preschool–school aged | Toddler–school-aged | Teens–adults | Adults |
| Asthma duration, yr | 10–15 | 15–25 | >20 |
<10 | |
| Atopy measures | |||||
| ≥1 pos SPT, % | 85 | 78 | 83 | 66 | 64 |
| Baseline FEV1% predicted* | 103 (97–109) | 83 (76–90) | 59 (48–66) | 44 (32–52) | 75 (67–81) |
| Maximal FEV1% predicted* | 113 (108–117) | 95 (88–99) | 77 (68–83) | 57 (48–68) | 82 (78–90) |
| Summary Lung Function | Normal | Reversible to normal | Obstructed, more reversible | Obstructed, less reversible | Borderline normal |
| Medications, % subjects | |||||
| High-dose ICS | 10 | 28 | 63 | 78 | 49 |
| OCS | 11 | 10 | 39 | 47 | 17 |
| Taking ≥3 controllers | 19 | 29 | 56 | 67 | 54 |
| Health care utilization, past yr, % subjects | |
||||
| ≥3 exacerbations with OCS | 11 | 19 | 46 | 42 | 36 |
| Hospitalization for asthma | 7 | 9 | 23 | 28 | 15 |
Definition of abbreviations: BMI = body mass index; ICS = inhaled corticosteroids; IQR = interquartile range; OCS = oral corticosteroids; SPT = skin prick testing.
*
Data expressed as median (25–75% [IQR]). Table adapted with permission from Ref. 11.