Table 2.
Characteristics of participants
| Number of participants | 20496 | |
| 1995 | 9959 (48.6%) | |
| 1996 | 10537 (51.4%) | |
| Age (years) | ||
| 30–39 | 5340 (26.1%) | |
| 40–49 | 4822 (23.5%) | |
| 50–59 | 3821 (18.6%) | |
| 60–69 | 3371 (16.5%) | |
| 70–79 | 2365 (11.5%) | |
| ≥80 | 777 (3.8%) | |
| Sex | ||
| Male | 9643 (47.1%) | |
| Female | 10853 (53.0%) | |
| Smoking status | ||
| Current | 5191 (25.3%) | |
| Ex-regular | 6187 (30.2%) | |
| Never regular | 9115 (44.5%) | |
| Reported respiratory conditions | ||
| Reported asthma diagnosis | 2180 (10.6%) | |
| First wheezed before age 30 years |
1289 (6.3%) | |
| Reported diagnosis of chronic bronchitis or emphysema |
291 (1.4%) | |
| Other respiratory condition* | 489 (2.4%) | |
| Reported respiratory symptoms | ||
| Dyspnoea | 5425 (26.5%) | |
| MRC grade 3 or worse | 2223 (10.9%) | |
| Wheeze | 4422 (21.6%) | |
| Chronic cough | 2783 (13.6%) | |
| Chronic phlegm | 2181 (10.6%) | |
| Frequent winter bronchitis | 3447 (16.8%) | |
| Any of the above respiratory symptoms |
8410 (41.0%) | |
| Airways obstruction† | ||
| GOLD | 2872 (14.0%) | |
| NICE | 1305 (6.4%) | |
| Single LLN | 1796 (8.8%) | |
| Double LLN | 733 (3.6%) | |
| Clinically significant COPD†, ‡ | Reporting diagnosis of chronic bronchitis/emphysema |
|
| GOLD+symptoms | 91628 (7.9%) | 145 (8.9%) |
| NICE+symptoms | 971 (4.7%) | 131 (13.5%) |
| Single LLN+symptoms | 1072 (5.2%) | 113 (10.5%) |
| Double LLN+symptoms | 571 (2.8%) | 99 (17.3%) |
*
Excluding hayfever.
†
Prebronchodilator values with childhood asthmatics reclassified (see the Methods section).
‡
Respiratory symptoms and airflow obstruction.
GOLD=FEV1/FVC <0.7; NICE=FEV1/FVC <0.7 and FEV1 <80% predicted; single LLN=FEV1/FVC <5th percentile of healthy never-smoking population; double LLN=FEV1/FVC <5th percentile and FEV1 <5th percentile.
COPD, chronic obstructive pulmonary disease; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; GOLD, Global Initiative for Chronic Obstructive Lung Disease; LLN, lower limit of normal; MRC, Medical Research Council; NICE, National Institute for Health and Clinical Excellence.