Table 4– Odds ratio for airflow obstruction by certain baseline characteristics in never-smokers
VariableFemales#Males
Subjects n (%)Crude OR (95% CI)+Adjusted OR (95% CI)+,§Subjects n (%)Crude OR (95% CI)+Adjusted OR (95% CI)+,§
Region type
 Urban4377 (3.4)1.001.00516 (3.1)1.001.00
 Rural7096 (4.5)1.33 (1.28–1.38)1.17 (1.12–1.22)1024 (7.6)2.59 (2.33–2.89)2.15 (1.89–2.45)
Age at baseline years
 30–391113 (2.4)1.00 (0.94–1.06)1.00 (0.94–1.07)94 (2.0)1.00 (0.82–1.23)1.00 (0.81–1.24)
 40–492143 (2.4)1.00 (0.96–1.04)1.08 (1.03–1.13)143 (2.0)1.00 (0.85–1.18)1.09 (0.92–1.30)
 50–593480 (3.9)1.67 (1.62–1.73)1.65 (1.59–1.71)339 (4.3)2.18 (1.95–2.43)2.05 (1.83–2.30)
 60–693110 (6.8)3.03 (2.93–3.15)3.00 (2.88–3.11)560 (7.8)4.05 (3.72–4.42)3.81 (3.49–4.16)
 70–791627 (11.2)5.21 (4.95–5.49)5.15 (4.86–5.46)404 (11.1)5.96 (5.38–6.61)6.28 (5.59–7.06)
Education
 No formal school4624 (6.4)3.86 (3.75–3.98)1.17 (1.12–1.23)251 (11.3)4.50 (3.94–5.13)1.16 (0.99–1.36)
 Primary school3888 (4.4)2.57 (2.48–2.65)0.94 (0.91–0.97)696 (8.7)3.33 (3.09–3.60)1.01 (0.93–1.11)
 Middle/high school2733 (2.4)1.39 (1.34–1.45)0.88 (0.84–0.92)458 (3.0)1.10 (1.00–1.20)0.78 (0.70–0.87)
 College/university228 (1.7)1.00 (0.88–1.14)1.00 (0.87–1.15)135 (2.8)1.00 (0.84–1.19)1.00 (0.82–1.23)
Household income yuan per year
 <49992351 (8.7)3.01 (2.88–3.14)1.63 (1.55–1.72)323 (12.7)5.06 (4.50–5.68)2.10 (1.82–2.42)
 5000–99992621 (4.7)1.57 (1.51–1.63)1.38 (1.33–1.45)307 (6.8)2.53 (2.25–2.84)1.88 (1.65–2.14)
 10 000–19 9992993 (3.5)1.16 (1.11–1.20)1.21 (1.17–1.26)459 (5.3)1.96 (1.78–2.15)1.71 (1.55–1.88)
 20 000–34 9992023 (2.8)0.93 (0.89–0.97)1.01 (0.96–1.06)268 (3.3)1.19 (1.05–1.34)1.20 (1.05–1.37)
 ≥35 0001485 (3.1)1.00 (0.95–1.05)1.00 (0.94–1.06)183 (2.8)1.00 (0.86–1.16)1.00 (0.84–1.19)
BMI kg·m−2
 <18.51034 (8.7)2.51 (2.36–2.68)2.04 (1.91–2.19)157 (14.4)3.57 (3.01–4.23)2.53 (2.10–3.04)
 18.5–<22.54338 (4.6)1.27 (1.23–1.31)1.25 (1.21–1.29)643 (6.9)1.57 (1.45–1.71)1.29 (1.18–1.40)
 22.5–<253026 (3.7)1.00 (0.96–1.04)1.00 (0.96–1.04)403 (4.5)1.00 (0.90–1.11)1.00 (0.90–1.11)
 25–<302647 (3.1)0.85 (0.82–0.88)0.82 (0.79–0.86)304 (3.1)0.67 (0.60–0.76)0.76 (0.67–0.85)
 ≥30428 (3.1)0.84 (0.76–0.92)0.81 (0.74–0.90)33 (3.1)0.68 (0.48–0.96)0.89 (0.63–1.28)
Ever diagnosed with TB
 No11 226 (4.0)1.001.001465 (5.0)1.001.00
 Yes247 (7.9)2.08 (1.82–2.37)2.36 (2.06–2.71)75 (9.6)2.03 (1.59–2.60)1.81 (1.40–2.34)
  • All p-values for trend or heterogeneity <0.0001 except for adjusted odds ratios for years of education in males (p=0.0016). BMI: body mass index; TB: tuberculosis. #: n=287 153; : n=30 246; +: for variables with more than two categories, odds ratios and confidence intervals are floated; §: odds ratios for airflow obstruction (Global Initiative for Chronic Obstructive Lung Disease (GOLD) grade ≥1) were adjusted for age, education, household income, region and age by region.