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Table 2 Prevalence of COPD among participants by smoking status and PM2.5 concentration in this study

From: Joint association of cigarette smoking and PM2.5 with COPD among urban and rural adults in regional China

 

Prevalence of COPD

Overall (N = 3047)

Smoking statusa

Annual mean PM2.5 concentrationb (μg/m3)

Non-smokers (N = 2073)

Smokers (N = 1334)

< 75 (N = 2267)

≥ 75 (N = 1140)

 

n

% (95%CI)

P value

n

% (95%CI)

P value

n

% (95%CI)

P value

n

% (95%CI)

P value

n

% (95%CI)

P value

Overall

407

11.9 (10.9, 13.0)

 

132

6.4 (5.3, 7.4)

 

275

20.6 (18.4, 22.8)

 

246

10.9 (9.6, 12.1)

 

161

14.1 (12.1, 16.1)

 

Gender

  

< 0.001

  

0.017

  

0.792

  

< 0.001

  

< 0.001

 Men

285

18.3 (16.3, 20.2)

 

31

9.3 (6.2, 12.4)

 

254

20.7 (18.4, 23.0)

 

177

16.8 (14.6, 19.1)

 

108

21.2 (17.6, 24.7)

 

 Women

122

6.6 (5.5, 7.7)

 

101

5.8 (4.7, 6.9)

 

21

19.6 (12.1, 27.2)

 

69

5.7 (4.4, 7.0)

 

53

8.4 (6.2, 10.6)

 

Age (years)

  

< 0.001

  

< 0.001

  

< 0.001

  

< 0.001

  

< 0.001

 40–49

28

3.2 (2.1, 4.4)

 

14

2.3 (1.1, 3.5)

 

14

5.3 (2.6, 8.0)

 

25

4.2 (2.6, 5.8)

 

3

1.1 (0, 2.4)

 

 50–59

89

7.9 (6.3, 9.5)

 

29

4.2 (2.7, 5.6)

 

60

13.9 (10.7, 17.2)

 

60

7.8 (5.9, 9.7)

 

29

8.0 (5.2, 10.8)

 

 60–69

175

17.2 (14.8, 19.5)

 

49

8.7 (6.3, 11.0)

 

126

27.8 (23.6, 31.9)

 

99

14.9 (12.2, 17.6)

 

76

21.5 (17.2, 25.7)

 

 70+

115

29.1 (24.6, 33.6)

 

40

19 (13.7, 24.4)

 

75

40.5 (33.5, 47.6)

 

62

25.7 (20.2, 31.2)

 

53

34.4 (26.9, 41.9)

 

Residence

  

0.112

  

0.885

  

0.068

  

0.530

   

 Urban

215

12.8 (11.2, 14.4)

 

63

6.3 (4.8, 7.8)

 

152

22.6 (19.5, 25.8)

 

54

10.1 (7.6, 12.7)

 

161

14.1 (12.1, 16.1)

 

 Rural

192

11.1 (9.6, 12.6)

 

69

6.4 (5.0, 7.9)

 

123

18.6 (15.6, 21.5)

 

192

11.1 (9.6, 12.6)

 

0

  

Educational attainment (years)

  

< 0.001

  

0.069

  

< 0.001

  

0.418

  

< 0.001

 9−

356

12.8 (11.6, 14.0)

 

116

6.8 (5.6, 8.0)

 

240

22.3 (19.8, 24.7)

 

210

11.1 (9.7, 12.6)

 

146

16.3 (13.9, 18.8)

 

 10–12

43

8.4 (6.0, 10.8)

 

13

4.3 (2.0, 6.6)

 

30

14.4 (9.6, 19.1)

 

32

10.1 (6.8, 13.4)

 

11

5.7 (2.4, 9.0)

 

 13+

8

6.8 (2.3, 11.4)

 

3

4.3 (0.0, 9.0)

 

5

10.6 (1.8, 19.5)

 

4

6.2 (0.3, 12.2)

 

4

7.5 (0.4, 14.7)

 

Occupationc

  

0.628

  

0.153

  

0.288

  

0.353

  

0.664

 Blue collar

289

12.1 (10.8, 13.4)

 

104

6.8 (5.6, 8.1)

 

185

21.5 (18.7, 24.2)

 

192

11.2 (9.7, 12.7)

 

97

14.5 (11.8, 17.2)

 

 White collar

118

11.5 (9.6, 13.5)

 

28

5.1 (3.3, 6.9)

 

90

19.0 (15.5, 22.6)

 

54

9.8 (7.3, 12.3)

 

64

13.6 (10.5, 16.7)

 

Biomass used

  

< 0.001

  

0.011

  

0.025

  

0.036

  

< 0.001

 No

270

10.7 (9.5, 11.9)

 

87

5.6 (4.4, 6.7)

 

183

19.1 (16.6, 21.5)

 

161

10.0 (8.5, 11.4)

 

109

12.0 (9.9, 14.2)

 

 Yes

137

15.4 (13.0, 17.8)

 

45

8.7 (6.3, 11.2)

 

92

24.6 (20.2, 29.0)

 

85

13.0 (10.4, 15.6)

 

52

22.1 (16.8, 27.4)

 

Parental history of respiratory diseasese

  

0.012

  

0.011

  

0.127

  

0.078

  

0.100

 Negative

255

11.0 (9.7, 12.3)

 

76

5.4 (4.2, 6.6)

 

179

19.5 (16.9, 22.0)

 

159

10.1 (8.6, 11.6)

 

96

12.9 (10.5, 15.3)

 

 Positive

152

14.0 (11.9, 16.1)

 

56

8.3 (6.3, 10.4)

 

96

23.1 (19.1, 27.2)

 

87

12.6 (10.1, 15.1)

 

65

16.5 (12.8, 20.1)

 

Body weight status (BMI)f

  

< 0.001

  

0.701

  

< 0.001

  

0.024

  

0.002

 24−

189

14.6 (12.7, 16.5)

 

52

6.6 (4.9, 8.4)

 

137

26.7 (22.9, 30.5)

 

112

12.7 (10.5, 14.9)

 

77

18.5 (14.7, 22.2)

 

 24–27

169

11.3 (9.7, 12.9)

 

60

6.5 (4.9, 8.1)

 

109

18.8 (15.6, 21.9)

 

103

10.4 (8.5, 12.3)

 

66

12.8 (9.9, 15.7)

 

 28+

49

8 (5.9, 10.2)

 

20

5.4 (3.1, 7.7)

 

29

12.1 (8.0, 16.2)

 

31

7.7 (5.1, 10.3)

 

18

8.6 (4.8, 12.4)

 
  1. aSmokers referred to either current (continuously smoked at least one cigarette every day for at least 1 year or totally smoked 18+ packs in a year) or former (met the criteria of current smokers previously but now did not smoke for > 1 year) smokers, while non-smokers means the never-smokers. Non-smokers were those not meeting the current/former smokers’ criteria
  2. bClassification of PM2.5 was based on “ambient air quality standard (GB3095-2010)” issued by China State Department of Environment Protection in 2010
  3. cBlue collar: including farmer, factory worker, forestry worker, fisher, salesperson, house-worker and vehicle driver; White collar: including office worker, teacher, doctor, academic researcher and government official
  4. dTypically using wood, grass, crop residues or animal waste for cooking or heating
  5. ePositive parental history of respiratory diseases referred to that either of parents has been diagnosed with any of the following respiratory diseases: asthma, chronic bronchitis, emphysema, COPD, pulmonary heart disease, or bronchiectasis
  6. fBody weight status was assessed based on BMI cutoffs recommended for Chinese adults
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