Group demographics
| Severe nonsmoking asthma | Smokers and ex-smokers with severe asthma# | Mild/moderate nonsmoking asthma | Healthy nonsmoking controls | p-value | |
| Subjects n | 311 | 110 | 88 | 101 | |
| Age years | 51.01±0.8 (n=311) | 54.51±1.08 (n=110) | 41.66±1.65 (n=88) | 38.85±1.34 (n=101) | <0.001 |
| Age at diagnosis years | 20 (7−38) (n=302) | 38 (20−48) (n=109) | 14 (6−32) (n=83) | NA | <0.001 |
| Females | 205/311 (66%) | 56/110 (51%) | 44/88 (50%) | 39/101 (39%) | <0.001 |
| BMI kg·m−2 | 29.11±0.36 (n=311) | 29.59±0.6 (n=110) | 25.73±0.47 (n=88) | 25.31±0.36 (n=101) | <0.001 |
| BMI >30 kg·m−2 | 120/311 (38.6%) | 44/110 (40%) | 16/88 (18.18%) | 12/101 (11.88%) | <0.001 |
| Serum IgE IU·mL−1 | 119.5 (45−342) (n=302) | 126 (63−328) (n=104) | 89.4 (49−244) (n=85) | 23.45 (9−65) (n=98) | <0.001 |
| FEV1 % pred | 67.5±1.26 (n=308) | 67.2±1.84 (n=110) | 89.5±1.86 (n=87) | 101.76±1.29 (n=101) | <0.001 |
| FVC % pred | 87.2±1.12 (n=308) | 89.7±1.74 (n=110) | 104.5±2.02 (n=87) | 107.8±1.3 (n=101) | <0.001 |
| FEV1/FVC ratio | 0.64±0.01 (n=308) | 0.61±0.01 (n=110) | 0.72±0.01 (n=87) | 0.79±0.01 (n=101) | <0.001 |
| Exacerbations in previous year n | 2.48±0.13 (n=310) | 2.55±0.26 (n=110) | 0.38±0.08 (n=88) | NA | <0.001 |
| Smoking history pack-years | 2 (1−4) (n=47) | 17.38 (10−26) (n=110) | 4 (1−4) (n=13) | 0.9 (0−3) (n=20) | <0.001 |
| Intubation (ever) | 35/307 (11%) | 6/109 (6%) | 0/87 (0%) | NA | 0.083 |
| ICU admission (ever) | 80/307 (26%) | 18/109 (17%) | 1/86 (1%) | NA | <0.001 |
| Atopy test positive | 213/272 (78.3%) | 62/87 (71.3%) | 72/78 (92.3%) | 36/78 (46.2%) | <0.001 |
Data are presented as mean±se, median (interquartile range) or n/N (%), unless otherwise stated. BMI: body mass index; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; ICU: intensive care unit; NA: not applicable. #: 42 current smokers and 68 ex-smokers.