Table 4. Factors associated with the diagnoses of asthma, COPD, and the asthma–COPD overlap syndrome.

	Asthma only	Asthma+COPD	COPD only
Gender males	1	1	1
females	0.87 (0.72–1.04)	1.63 (1.15–2.31)	1.15 (0.92–1.44)
Age [20–44]	1	1	1
[45–64]	0.60 (0.47–0.77)	1.12 (0.75–1.69)	1.57 (1.20–2.07)
[65–85]	0.48 (0.3–0.77)	1.43 (0.76–2.70)	5.50 (3.75–8.08)
Smoking habits non-smoker	1	1	1
current smoker	1.27 (1.02–1.58)	1.70 (1.12–2.60)	3.16 (2.41–4.16)
ex smoker	0.99 (0.78–1.26)	1.56 (1.04–2.35)	1.56 (1.16–2.08)
Education compulsory	1	1	1
high school	1.26 (0.99–1.6)	0.45 (0.31–0.65)	0.70 (0.55–0.90)
college/university	1.61 (1.24–2.09)	0.30 (0.17–0.51)	0.38 (0.26–0.57)
Industries nearby	1.00 (0.78–1.27)	0.91 (0.55–1.50)	1.30 (0.98–1.73)
Heavy traffic occasional/none	1	1	1
frequent	1.00 (0.78–1.27)	0.91 (0.55–1.50)	1.30 (0.98–1.73)
constant	1.38 (1.07–1.77)	1.57 (0.98–2.50)	1.67 (1.24–2.24)

Relative Risk Ratios* (RRR) with 95%CI, with subjects without diagnosed diseases as reference group. Statistically significant associations are shown in bold.

^*adjusted for all variables presented in this table plus design confounders (season, cumulative percentile rank of response, type of interview, GEIRD centre).