Prevalence of symptom-based COPD, doctor-diagnosed COPD or either, by second resurvey characteristics
| Characteristics | Study population | Symptom-based COPD* % (95% CI) | Doctor-diagnosed COPD† % (95% CI) | Symptom-based or doctor-diagnosed COPD‡ % (95% CI) |
| All participants (%) | 25 011 | 612 (2.4) | 1193 (4.8) | 1586 (6.4) |
| Age at resurvey (years) | ||||
| 30–49 | 5500 | 1.7 (1.4 to 2.1) | 2.6 (2.2 to 3.0) | 3.8 (3.3 to 4.4) |
| 50–59 | 7722 | 2.1 (1.8 to 2.5) | 3.6 (3.2 to 4.0) | 5.2 (4.7 to 5.7) |
| 60–69 | 7449 | 2.9 (2.5 to 3.3) | 6.0 (5.4 to 6.5) | 7.7 (7.0 to 8.3) |
| 70+ | 4340 | 3.3 (2.8 to 3.9) | 7.5 (6.7 to 8.3) | 9.3 (8.4 to 10.2) |
| Sex | ||||
| Men | 9580 | 3.7 (3.3 to 4.0) | 5.4 (5.0 to 5.9) | 7.9 (7.4 to 8.5) |
| Women | 15 431 | 1.7 (1.5 to 1.9) | 4.3 (4.0 to 4.6) | 5.3 (5.0 to 5.7) |
| Area | ||||
| Rural | 14 235 | 2.8 (2.5 to 3.1) | 4.7 (4.4 to 5.1) | 6.5 (6.1 to 6.9) |
| Urban | 10 776 | 2.0 (1.7 to 2.3) | 4.8 (4.4 to 5.2) | 6.2 (5.7 to 6.6) |
| Education | ||||
| None | 5068 | 2.3 (1.2 to 3.4) | 4.0 (3.1 to 4.9) | 5.7 (4.2 to 7.1) |
| Primary | 8032 | 2.2 (1.9 to 2.5) | 4.5 (4.0 to 5.0) | 5.9 (5.3 to 6.4) |
| Secondary or tertiary | 11 911 | 2.5 (2.1 to 3.0) | 4.7 (4.1 to 5.3) | 6.6 (5.9 to 7.3) |
| Household income (¥) | ||||
| <10 000 | 2175 | 2.9 (2.2 to 3.5) | 5.5 (4.2 to 6.7) | 7.3 (6.0 to 8.7) |
| 10 000–19 999 | 3079 | 3.1 (2.1 to 4.0) | 4.8 (3.6 to 6.0) | 6.7 (5.3 to 8.0) |
| ≥20 000 | 19 757 | 2.4 (2.1 to 2.6) | 4.8 (4.5 to 5.1) | 6.3 (6.0 to 6.7) |
| Smoking status | ||||
| Never | 18 274 | 1.8 (1.6 to 2.0) | 4.6 (4.2 to 4.9) | 5.7 (5.3 to 6.1) |
| Ex-regular | 1611 | 3.6 (1.9 to 5.4) | 11.1 (9.3 to 12.9) | 12.8 (10.6 to 15.0) |
| Current regular | 5126 | 2.9 (2.4 to 3.4) | 3.7 (2.6 to 4.8) | 5.9 (4.8 to 7.0) |
| Body mass index (kg/m²) | ||||
| <18.5 | 950 | 4.0 (2.7 to 5.2) | 8.9 (7.0 to 10.8) | 10.7 (8.6 to 12.7) |
| 18.5–25.0 | 14 289 | 2.3 (2.0 to 2.5) | 4.5 (4.1 to 4.8) | 5.9 (5.5 to 6.3) |
| ≥25.0 | 9772 | 2.5 (2.2 to 2.9) | 4.9 (4.4 to 5.4) | 6.7 (6.2 to 7.2) |
| Physical activities (MET-hour/day) | ||||
| <10 | 14 129 | 2.7 (2.3 to 3.1) | 4.9 (4.5 to 5.3) | 6.6 (6.1 to 7.2) |
| 10–14 | 1722 | 2.3 (1.6 to 3.1) | 4.3 (3.2 to 5.3) | 5.6 (4.4 to 6.8) |
| ≥14 | 9160 | 2.3 (1.8 to 2.7) | 4.8 (4.1 to 5.6) | 6.3 (5.5 to 7.1) |
| Self-assessed health status | ||||
| Good/excellent | 10 943 | 1.5 (1.3 to 1.7) | 2.7 (2.4 to 3.0) | 3.8 (3.5 to 4.2) |
| Fair | 10 851 | 2.4 (2.1 to 2.7) | 4.9 (4.5 to 5.4) | 6.7 (6.2 to 7.1) |
| Poor | 3217 | 5.4 (4.6 to 6.2) | 10.0 (8.9 to 11.1) | 12.9 (11.7 to 14.1) |
↵*Symptom-based COPD are those with self-reported chronic cough, that is, productive cough for at least 3 months for two consecutive years.
↵†COPD defined by history of doctor diagnosis of COPD, where COPD=COPD and/or chronic bronchitis and/or emphysema.
↵‡Either * or †; standardised for region, age group and gender as appropriate.
COPD, chronic obstructive pulmonary disease; MET, metabolic equivalent of task.