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Table 7 Trends in betas (mL/yr) by level of various factorsa

From: Systematic review of the evidence relating FEV1decline to giving up smoking

       

Trend (SE)b

  

Factor

Levels

Study no.

Ref.

Sex

Age range at baseline

 

Continuing smokers

Quitters

Ex-smokers

Baseline FEV1 (cL/m3)

65+, 55-64, 1-54

13

Fletcher et al. [6]

Male

30-59

Mean

10.0 (1.5)***

4.0 (8.8)

4.8 (3.5)

      

Diffc

Base

6.2 (8.9)

5.1 (3.8)

Baseline FEV1 (mL)

High, middle, low

4

Burchfiel et al. [11]

Male

45-68

Mean

-24.8 (1.6)***

-16.1 (5.3)**

 
      

Diff

Base

-8.8 (5.6)

 

Baseline FEV1 (mL/m3)

500+, 1-499

45

Townsend [73]

Male

35-57

Mean

28.1 (8.6)**

21.2 (15.6)

 
      

Diff

Base

6.9 (17.8)

 

Baseline FEV1/FVC (%)

80+, 70-79, 1-69

5

Burrows et al. [10]

Male

20-70

Mean

27.9 (4.2)***

 

-3.4 (5.5)

      

Diff

Base

 

31.3 (6.9)***

Obstruction at baseline

None, mild

13

Fletcher and Peto [31]

Male

30-59

Mean

24.8 (16.4)

 

7.0 (9.4)

      

Diff

Base

 

17.8 (18.9)

Obstruction at baseline

None, mild

13

Fletcher et al. [6]

Male

30-59

Mean

22.1 (11.4)

 

4.0 (8.5)

      

Diff

Base

 

18.1 (14.3)

Doctor visits for LRId

0-0.24, 0.25-0.49, 0.50-0.99, 1.00-1.49, 1.50+

43

Kanner et al. [70]

Male

35-60

Mean

3.5 (0.8)***

 

2.9 (1.9)

      

Diff

Base

 

0.7 (2.0)

Respiratory symptoms at baseline

No, Yes

29

Sherman et al. [53]

Male

25-74

Mean

4.6 (4.0)

 

4.3 (3.1)

      

Diff

Base

 

0.3 (5.1)

Respiratory symptoms at baseline

No, Yes

29

Sherman et al. [53]

Female

25-74

Mean

1.9 (2.4)

 

-5.9 (5.0)

      

Diff

Base

 

7.8 (5.5)

Bronchodilator responsiveness

No, Yes

34

Vollmer et al. [60]

Both

25-54

Mean

22.0 (30.1)

46.0 (22.7)

 
      

Diff

Base

-24.0 (37.7)

 

Bronchodilator responsiveness

No, Yes

35

Vollmer et al. [60]

Both

25-54

Mean

10.0 (13.7)

14.0 (20.0)

 
      

Diff

Base

-4.0 (24.2)

 

Histamine responsiveness

No, Yes

32

Rijcken et al. [5]

Male

25-54

Mean

3.2 (7.9)

 

4.5 (9.4)

      

Diff

Base

 

-1.3 (12.3)

Histamine responsiveness

No, Yes

32

Rijcken et al. [5]

Female

25-54

Mean

5.8 (8.2)

 

5.9 (12.0)

      

Diff

Base

 

-0.1 (14.5)

Occupational exposure

None, low, high

7

Sunyer et al. [24]

Male

20-44

Mean

0.8

 

-1.1

      

Diff

Base

 

1.8

Occupational exposure

None, low, high

7

Sunyer et al. [24]

Female

20-44

Mean

1.2

 

6.2

      

Diff

Base

 

-5.0

Exposure to gas and fumes

None, low, high

7

Sunyer et al. [24]

Male

20-44

Mean

1.5

 

-2.9

      

Diff

Base

 

4.4

Exposure to gas and fumes

None, low, high

7

Sunyer et al. [24]

Females

20-44

Mean

-3.2

 

5.6

      

Diff

Base

 

-8.9

Biological dust exposure

None, low, high

7

Sunyer et al. [24]

Males

20-44

Mean

0.2

 

2.5

      

Diff

Base

 

-2.3

Biological dust exposure

None, low, high

7

Sunyer et al. [24]

Females

20-44

Mean

6.8

 

5.6

      

Diff

Base

 

1.2

Mineral dust exposure

None, low, high

7

Sunyer et al. [24]

Males

20-44

Mean

0.0

 

2.3

      

Diff

Base

 

-2.3

Mineral dust exposure

None, low, high

7

Sunyer et al. [24]

Females

20-44

Mean

2.0

 

6.5

      

Diff

Base

 

-4.5

  1. aFEV1, forced expiratory volume in 1 second; FVC, forced vital capacity. bThe trend is the estimated weighted increase in beta per level of exposure, except for study 7 where it is unweighted as no SEs are available. Trends are underlined if significant at P < 0.05. cThe difference in the trend compared to continuing smokers. Significant differences in trends are indicated by *P < 0.05, **P < 0.01 and ***P < 0.001. dLRI, lower respiratory infection.