| Fixed cut-off (70%) | Subjects without AO (n = 5664) | Misidentified subjects (n = 318) | Subjects with AO (n = 267) | p Value (misidentified subjects vs those without AO) | p Value (misidentified subjects vs those with AO) |
| AO− | AO− | AO+ | |||
| LLN | AO− | AO+ | AO+ | ||
| Women (%) | 52.8 | 64.2 | 39.7 | <0.001 | <0.001 |
| 0.007 | <0.001 | ||||
| Age (years) (%) | |||||
| <30 | 32.9 | 39.6 | 19.5 | ||
| (30–40) | 40.9 | 41.2 | 37.1 | ||
| ⩾40 | 26.2 | 19.2 | 43.4 | ||
| Ever smokers | 56.5 | 58.4 | 65.9 | 0.521 | 0.061 |
| Median (IQR) No of pack-years* | 9.5 (4.2–17.7) | 9.5 (5.0–18.0) | 15.0 (5.0–27.0) | 0.303 | 0.004 |
| FEV1% pred (mean (SD)) | 107.1 (12.4) | 97.0 (11.2) | 84.7 (16.1) | <0.001 | <0.001 |
| FVC% pred (mean (SD)) | 108.6 (13.0) | 113.8 (13.3) | 109.5 (17.3) | <0.001 | <0.001 |
| BHR slope† (mean (SD)) | 7.84 (2.09) | 6.32 (2.46) | 5.57 (2.25) | <0.001 | 0.007 |
| High total IgE (%) | 22.9 | 31.5 | 37.0 | 0.001 | 0.178 |
| IgE sensitisation (%) | 32.5 | 42.0 | 53.5 | 0.001 | 0.008 |
| Chronic cough or phlegm (%) | 12.1 | 17.4 | 23.4 | 0.005 | 0.075 |
| Physician diagnosed asthma (%)‡ | 13.8 | 27.4 | 53.9 | <0.001 | <0.001 |
All variables were measured at the ECRHS I, unless stated otherwise.
*Among ever smokers.
†A low slope is indicative of a high BHR; p values were obtained after adjusting for baseline FEV1% predicted.
‡Self-reported diagnosis of asthma during their lifetime at the ECRHS II.
AO, airflow obstruction; BHR, bronchial hyperresponsiveness; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; LLN, lower limit of normal.