Table I.
Characteristics of Participants Stratified by Asthma Age of Onset
| No Asthma* |
Child Onset Asthma ≤18 years† |
Young Adult Onset Asthma 19 to 45 years‡ |
Late Adult Onset Asthma > 45 years§ |
|
|---|---|---|---|---|
| N=3371 | 2925 | 217 | 102 | 127 |
| Age, mean (SD), years | 65 (10) | 63 (10) | 62 (10) | 68 (9) |
| Female gender — % | 50 | 48 | 79 | 67 |
| Race/ethnicity — % | ||||
| White | 34 | 38 | 38 | 40 |
| Chinese-American | 19 | 11 | 6 | 10 |
| African American | 25 | 31 | 29 | 21 |
| Hispanic | 23 | 20 | 28 | 29 |
| Education, years — % | ||||
| < 12 | 17 | 11 | 19 | 17 |
| 12 | 18 | 10 | 12 | 20 |
| > 12 | 65 | 79 | 69 | 63 |
| Asthma age-of-onset, median (IQR) | n/a | 8 (4–13) | 35 (30–40) | 57 (50–64) |
| Age at remission, median (IQR) | n/a | 17 (12–25) | 40 (33–45) | 57 (50–67) |
| Taking asthma medications, — %¶ | 0 | 29 | 47 | 60 |
| Wheezing in last 12 months, — % | 0 | 35 | 48 | 54 |
| Current asthma, — % | 0 | 52% | 55% | 91% |
| Hay fever – % | 29 | 62 | 55 | 48 |
| Height, mean (SD), cm | 166 (10) | 167 (10) | 163 (8) | 163 (10) |
| Weight, mean (SD), lbs | 169 (37) | 182 (42) | 178 (39) | 175 (37) |
| Waist circumference, mean (SD), cm | 96 (13) | 100 (16) | 101 (16) | 103 (15) |
| Body mass index, mean (SD), kg/m2 | 28 (5) | 29 (6) | 31 (7) | 30 (6) |
| Cigarette smoking status, — % | ||||
| Never | 51 | 50 | 50 | 40 |
| Past | 42 | 39 | 41 | 47 |
| Current | 8 | 11 | 9 | 13 |
| Cigarette pack years, median (IQR)# | 13 (3–30) | 16 (5–35) | 12 (6–23) | 24 (6–44) |
| Pipe-years, median (IQR)** | 21 (9–70) | 48 (25–120) | 9 (8–25) | 18 (4–30) |
| Urine cotinine, median (IQR) ng/ml | 7 (7–11) | 7 (7–19) | 7 (7–22) | 7 (7–12) |
| Household ETS, — % | 69 | 70 | 77 | 67 |
| Occupational exposures to dust — % | 34 | 46 | 45 | 39 |
| Family history of emphysema, — % | 3 | 7 | 6 | 10 |
| CT scanner type, — % | ||||
| Multi-detector CT | 39 | 41 | 35 | 39 |
| Electron-beam CT | 61 | 59 | 65 | 61 |
| Particulate Matter < 10 µm, mean % (SD) | 16 (7) | 15 (7) | 17 (7) | 15 (8) |
| FEV1, mean % predicted (SD) | 98 (16) | 83 (18) | 83 (21) | 82 (23) |
| FVC, mean % predicted (SD) | 97 (15) | 90 (16) | 90 (18) | 90 (19) |
| FEV1/FVC % (SD) | 77 (7) | 71 (10) | 72 (11) | 69 (13) |
Abbreviations: SD, standard deviation; IQR, inter-quartile range; CT, computed tomography; ETS, environmental tobacco smoke; FEV1, forced expiratory volume in one second; FVC, forced vital capacity
No asthma = no history of asthma, no current respiratory medication use, no wheezing in the last twelve months, and an FEV1/FVC ≥ lower limit of normal.
Child onset asthma = report of first asthma symptoms or diagnosis before age 19 years
Young adult onset asthma = report of first asthma symptoms or diagnosis between ages 19 to 45 years
Late adult onset asthma = report of first asthma symptoms or diagnosis between after age 45 years
Inhaled corticosteroids, β-agonists, leukotriene inhibitors
Among ever smokers
Among pipe smokers