Characteristic of the population
| Study characteristics | n (%)* | 95% CI |
| Age, years (mean, SD) (n=1334) | 44.8 (0.8) | 44.7 to 44.9 |
| Sex, % (n=1335) | ||
| Men | 684 (51.6) | 48.5 to 54.9 |
| Women | 651 (48.3) | 45.0 to 51.5 |
| Smoking history (n=1330) | ||
| Never, n (%) | 566 (45.3) | 42.1 to 48.6 |
| Past, n (%) Pack-years, median (IQR) (n=1292) | 394 (29.6) 7.5 (2–17) | 26.7 to 32.6 |
| Current, n (%) Pack-years, median (IQR) (n=1292) | 370 (25.1) 21 (10–30) | 22.4 to 27.9 |
| Currently employed, n (%) (n=1332) | 1136 (87.4) | 85.2 to 89.3 |
| Fixed airflow obstruction (AO) | ||
| Fixed AO-GOLD (n=1335) | 113 (6.0) | 4.8 to 7.6 |
| Stage I: FEV1/FVC <0.7 and FEV1 ≥80% | 62 (3.7) | 2.7 to 5.1 |
| Stage II: FEV1/FVC <0.7 and FEV1 <80% | 51 (2.3) | 1.7 to 3.2 |
| Fixed AO-LLN (n=1335) | 112 (6.0) | 4.8 to 7.5 |
| Chronic bronchitis (n=1322) | 246 (8.7) | 7.6 to 9.9 |
| Respiratory symptoms | ||
| Chronic cough (n=1316) | 185 (8.8) | 7.4 to 10.3 |
| Chronic phlegm (n=1317) | 171 (6.8) | 5.8 to 8.1 |
| Dyspnoea (n=1334) | 227 (12.1) | 10.4 to 14.1 |
*The estimated prevalences were calculated using inverse-probability-of-inclusion weights to adjust for the enriched sample of the fifth decade follow-up survey.
AO, airflow obstruction; GOLD, Global Obstructive Lung Disease; LLN, lower limit of normal.