Prevalence of chronic obstructive pulmonary disease(COPD)# by age, sex, ethnicity, smoking status and pack-yrs
| Subjects with COPD/total (%) | 95% CI | |
| Age yrs | ||
| Overall | 116/749 | |
| 25–39 | 7/125 (5.6) | 2.2–11.2 |
| 40–49 | 6/133 (4.5) | 1.7–9.6 |
| 50–59 | 23/199 (11.6) | 7.5–16.8 |
| 60–69 | 47/188 (25.0) | 19.0–31.8 |
| ≥70 | 33/104 (31.7) | 23.0–41.6 |
| Sex | ||
| Male | 80/406 (19.7) | 16.0–23.9 |
| Female | 36/343 (10.5) | 7.5–14.2 |
| Ethnicity | ||
| New Zealand European | 98/654 (15.0) | 12.3–18.0 |
| Maori | 6/26 (23.1) | 9.0–43.7 |
| Other¶ | 12/56 (17.7) | 9.5–28.9 |
| Smoking status+ | ||
| Nonsmoker | 45/376 (12.0) | 8.9–15.7 |
| Current smoker | 20/76 (26.3) | 16.9–37.7 |
| Ex-smoker | 51/297 (17.2) | 13.1–22.0 |
| Pack-yrs | ||
| 0–9 | 17/185 (9.2) | 5.4–14.3 |
| 10–19 | 16/82 (19.5) | 11.6–29.7 |
| ≥20 | 38/106 (35.9) | 26.8–45.7 |
CI: confidence interval. #: defined according to Global Initiative for Chronic Obstructive Lung Disease criteria, i.e. post-bronchodilator forced expiratory volume in one second/forced vital capacity <0.7; ¶: mainly Asian and Pacific islanders; +: a further 30 subjects were tobacco smokers but not smokers of cigarettes.