Estimate of prevalence according to diagnostic criteria
| Criteria | Surveys n | Pooled prevalence % (95% CI) |
| COPD | 37 | 7.6 (6–9.5) |
| Spirometry | 26 | 9.2 (7.7–11) |
| Reported by patient | 7 | 4.9 (2.8–8.3) |
| Diagnosed by a doctor | 4 | 5.2 (3.3–7.9) |
| Clinical/radiological examination | 1 | 13.7 (12.9–14.5) |
| Chronic bronchitis | 38 | 6.4 (5.3–7.7) |
| Productive moist cough | 29 | 6.7 (5.4–8.2) |
| Reported by patient | 15 | 5.3 (3.9–7.1) |
| Emphysema | 8 | 1.8 (1.3–2.6) |
| Clinical/radiological examination | 1 | 3.2 (2.8–3.6) |
| Reported by patient | 7 | 1.7 (1.2–2.5) |
COPD: chronic obstructive pulmonary disease. Modified and reproduced from [14] with permission from the publisher.