Sex- and age-adjusted prevalence of sociodemographic characteristics, environmental exposures and risk factors at baseline
| Healthy | Asthma alone | ACOS | COPD alone | Overall p-value# | |
| Subjects | 5659 | 941 | 218 | 166 | |
| Female | 52.2 (50.8–53.6) | 61.2 (58.0–64.3)*** | 47.7 (41.0–54.3) | 47.5 (39.9–55.2) | <0.001 |
| Age >35 years | 50.8 (47.8–53.7) | 44.2 (40.1–48.2)** | 50.5 (43.2–57.7) | 60.4 (52.5–68.3)* | <0.001 |
| Low education | 6.7 (3.7–9.8) | 7.4 (3.8–11.0) | 7.9 (3.3–12.5) | 7.0 (2.4–11.7) | 0.80 |
| Lifetime smoker (>0 versus 0 pack-years smoked) | 55.1 (52.6–57.7) | 56.5 (52.6–60.3) | 64.1 (57.3–70.9)* | 72.4 (65.1–79.7)*** | <0.001 |
| Heavy smoker (≥15 versus 0.1–14.9 pack-years smoked)¶ | 27.1 (24.1–30.1) | 30.2 (25.1–35.2) | 35.1 (26.0–44.3) | 51.5 (40.6–62.3)*** | <0.001 |
| ETS | 57.1 (52.1–62.0) | 60.0 (54.3–65.7) | 58.3 (49.9–66.7) | 66.0 (57.2–74.4)* | 0.084 |
| Occupational exposure to vapours, dust, gas or fumes | 42.0 (37.2–46.7) | 45.9 (40.2–51.6)* | 43.7 (35.2–52.2) | 57.4 (48.1–66.7)*** | 0.001 |
| Family asthma | 11.1 (9.9–12.3) | 24.9 (21.6–28.1)*** | 26.3 (20.0–32.6)*** | 18.4 (12.1–24.7)** | <0.001 |
| Respiratory infection in childhood | 8.7 (7.4–10.1) | 17.4 (14.2–20.6)*** | 20.0 (14.0–25.9)*** | 13.0 (7.7–18.4) | <0.001 |
| Mother smoked during subject's childhood | 18.6 (13.3–23.8) | 19.1 (13.3–24.9) | 20.3 (12.8–27.7) | 17.5 (10.1–25.0) | 0.89 |
| Cat in childhood | 47.9 (44.3–51.4) | 47.8 (43.2–52.4) | 45.0 (37.4–52.6) | 55.6 (47.2–64.1) | 0.22 |
| Dog in childhood | 49.1 (44.3–53.8) | 48.4 (42.8–54.0) | 43.8 (35.5–52.1) | 50.7 (41.4–59.9) | 0.54 |
| Currently keeping a cat | 17.6 (14.5–20.6) | 20.9 (16.8–25.1)* | 15.6 (10.3–21.0) | 12.0 (6.7–17.3) | 0.013 |
| Currently keeping a dog | 15.6 (13.1–18.2) | 18.1 (14.6–21.7) | 17.1 (11.7–22.5) | 10.9 (5.7–16.1) | 0.092 |
| Mould in the house | 33.0 (28.4–37.6) | 35.7 (30.1–41.3) | 30.9 (23.1–38.6) | 30.9 (22.1–39.7) | 0.37 |
Data are presented as n or % (95% CI), unless otherwise stated. Data were adjusted using logistic regression models with the characteristic in the first column as the dependent variable, sex, age (with the exception of sex and age, which were only adjusted for age and sex, respectively), and disease status as independent variables, and a random intercept term for European Community Respiratory Health Survey centre and sample. ACOS: asthma–chronic obstructive pulmonary disease (COPD) overlap syndrome; ETS: environmental tobacco smoke. #: refers to the comparison across the groups; p<0.05 indicates that at least one of the prevalence rates is significantly different from the others; ¶: lifetime nonsmokers excluded. **: p<0.01; ***: p<0.001 for the comparison of the disease group with the healthy category.