Prevalence of Global Initiative for Chronic Obstructive Lung Disease(GOLD) chronic obstructive pulmonary disease (COPD) stages among nonsmokers
| Subjects n | Stage 0 | Stage I | Stage II–IV | |
| Sex | ||||
| Male | 2235 | 4.7 (3.9–5.7) | 2.3 (1.7–3.0) | 6.5 (5.6–7.6) |
| Female | 10236 | 4.8 (4.4–5.2) | 1.2 (1.0–1.5) | 3.1 (2.8–3.5) |
| Age yrs | ||||
| 40–49 | 4337 | 3.9 (3.3–4.5) | 0.4 (0.3–0.7) | 1.1 (0.9–1.5) |
| 50–59 | 3421 | 4.9 (4.2–5.6) | 1.0 (0.7–1.4) | 2.3 (1.9–2.9) |
| 60–69 | 2641 | 5.3 (4.5–6.2) | 1.8 (1.4–2.4) | 4.9 (4.1–5.8) |
| ≥70 | 2072 | 5.8 (4.9–6.9) | 3.7 (3.0–4.6) | 10.0 (8.8–11.4) |
| Education yrs | ||||
| 0 | 5592 | 4.8 (4.3–5.4) | 2.0 (1.7–2.4) | 5.7 (5.1–6.3) |
| 1–9 | 5945 | 4.5 (4.0–5.1) | 0.9 (0.7–1.2) | 2.2 (1.9–2.6) |
| ≥10 | 934 | 6.1 (4.7–7.8) | 1.2 (0.7–2.1) | 2.0 (1.3–3.2) |
| BMI kg·m−2 | ||||
| <18.5 | 424 | 5.0 (3.3–7.5) | 2.1 (1.1–4.0) | 12.5 (9.7–16.0) |
| 18.5–23.9 | 5830 | 4.3 (3.8–4.8) | 1.6 (1.3–1.9) | 4.0 (3.5–4.5) |
| 24.0–27.9 | 4591 | 5.0 (4.4–5.7) | 1.2 (0.9–1.6) | 2.7 (2.3–3.2) |
| ≥28.0 | 1626 | 5.7 (4.7–7.0) | 1.3 (0.8–2.0) | 3.4 (2.6–4.4) |
| Passive smoking# | ||||
| No | 2716 | 4.3 (3.6–5.2) | 1.1 (0.8–1.6) | 3.3 (2.7–4.1) |
| Yes | 9755 | 4.9 (4.5–5.3) | 1.5 (1.3–1.8) | 3.9 (3.5–4.3) |
| Respiratory disease in family | ||||
| None | 9761 | 4.0 (3.7–4.5) | 1.3 (1.1–1.5) | 3.4 (3.0–3.7) |
| 1 affected | 2176 | 6.4 (5.4–7.5) | 2.0 (1.5–2.7) | 4.7 (3.9–5.7) |
| ≥2 affected | 534 | 11.0 (8.7–14.0) | 1.9 (1.0–3.4) | 6.6 (4.7–9.0) |
| Chronic cough in childhood | ||||
| Recurrent | 335 | 14.0 (10.7–18.2) | 3.6 (2.0–6.2) | 9.3 (6.6–12.9) |
| Sometimes | 580 | 8.4 (6.4–11.0) | 1.7 (0.9–3.2) | 5.9 (4.2–8.1) |
| Seldom | 11556 | 4.3 (3.9–4.7) | 1.3 (1.2–1.6) | 3.5 (3.2–3.8) |
| Exposure to biomass for cooking | ||||
| Yes | 5565 | 4.5 (4.0–5.1) | 1.5 (1.2–1.8) | 4.5 (4.0–5.1) |
| No | 6906 | 5.0 (4.5–5.5) | 1.4 (1.1–1.7) | 3.1 (2.7–3.5) |
| Exposure to biomass for heating | ||||
| Yes | 906 | 3.0 (2.1–4.3) | 2.5 (1.7–3.8) | 5.0 (3.7–6.6) |
| No | 11565 | 4.9 (4.5–5.3) | 1.3 (1.1–1.6) | 3.6 (3.3–4.0) |
| Exposure to coal for cooking | ||||
| Yes | 9128 | 4.9 (4.4–5.3) | 1.4 (1.2–1.7) | 3.6 (3.2–4.0) |
| No | 3343 | 4.5 (3.8–5.2) | 1.5 (1.1–1.9) | 4.1 (3.5–4.9) |
| Exposure to coal for heating | ||||
| Yes | 1923 | 6.6 (5.6–7.8) | 1.0 (0.7–1.6) | 5.6 (4.7–6.7) |
| No | 10248 | 4.4 (4.0–4.8) | 1.5 (1.3–1.7) | 3.4 (3.1–3.8) |
| Poor ventilation in kitchen | ||||
| Yes | 4991 | 5.2 (4.6–5.9) | 1.6 (1.3–2.0) | 4.6 (4.0–5.2) |
| No | 7480 | 4.4 (4.0–4.9) | 1.3 (1.1–1.6) | 3.2 (2.8–3.6) |
| Occupational exposure to dusts/gases/fumes | ||||
| Yes | 2508 | 5.1 (4.3–6.1) | 2.0 (1.5–2.7) | 3.6 (2.9–4.4) |
| No | 9963 | 4.7 (4.3–5.1) | 1.3 (1.1–1.5) | 3.8 (3.4–4.2) |
Data are presented as % (95% confidence interval), unless otherwise stated. BMI: body mass index. #: defined as exposure to environmental tobacco smoke.