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Table 5 Relationship of beta (in mL/yr) to study characteristics adjusted for smoking group, sex and age

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

  

Unweighted analysis

Inverse variance-weighted analysis

Factor

Level

Number of betas

Beta (95% CI)

Pvaluea

Number of betas

Beta (95% CI)

Pvaluea

Sexb

Males

168

35.8 (33.1-38.4)

Base

150

34.6 (32.7-36.5)

Base

 

Females

88

23.9 (20.2-27.7)

---

72

28.3 (26.3-30.3)

---

 

Both

39

38.2 (32.5-43.9)

NS

39

40.7 (36.2-45.3)

+

Agec

< 40

47

13.2 (8.2-18.3)

Base

39

28.7 (25.8-31.5)

Base

 

40-49

78

33.9 (30.0-37.8)

+++

68

42.8 (39.6-46.1)

+++

 

50-69

123

37.8 (34.7-41.0)

+++

115

32.1 (30.1-34.1)

NS

 

70+

47

35.8 (30.7-40.9)

+++

39

27.9 (25.2-30.6)

NS

Length of follow-up period

Per year

295

-0.16 (-0.57 to 0.25)

NS

261

-0.03 (-0.27 to 0.21)

NS

Continent

North America

148

30.3 (27.5-33.1)

Base

114

29.0 (26.1-32.0)

Base

 

Europe

85

36.7 (32.9-40.5)

++

85

34.8 (31.5-38.1)

++

 

Asia

28

26.3 (19.7-32.8)

NS

28

31.6 (28.2-35.1)

NS

 

Australasia

12

41.9 (31.6-52.1)

+

12

42.1 (27.5-56.7)

NS

 

Multicountry

22

34.9 (27.2-42.7)

NS

22

34.3 (30.0-38.6)

NS

Final follow-up year

< 1980

78

27.0 (23.3-30.6)

Base

78

25.7 (22.8-28.6)

Base

 

1980-1989

98

42.3 (39.1-45.4)

+++

64

37.9 (34.8-41.1)

+++

 

1990-1999

91

26.0 (22.7-29.3)

NS

91

27.6 (25.0-30.3)

NS

 

2000+

28

35.6 (29.3-42.0)

+

28

35.8 (33.1-38.4)

+++

Publication year

< 1980

26

27.1 (20.1-34.1)

Base

26

26.3 (20.5-32.0)

Base

 

1980-1989

129

33.2 (30.2-36.3)

NS

129

35.0 (32.1-37.9)

++

 

1990-1999

99

34.2 (30.7-37.6)

NS

65

35.1 (32.5-37.8)

++

 

2000+

41

30.0 (24.4-35.5)

NS

41

30.2 (27.9-32.4)

NS

Population type

General

266

32.5 (30.4-34.6)

Base

232

32.7 (31.4-34.1)

Base

 

Diseased

29

32.9 (25.8-40.1)

NS

29

28.3 (22.3-34.4)

NS

Study type

Prospective

275

32.9 (30.8-35.0)

Base

243

32.7 (31.4-34.1)

Base

 

intervention

20

27.6 (19.2-36.0)

NS

18

28.4 (22.6-34.3)

NS

  1. a+++, ---P < 0.001; ++, -- P < 0.01; +, - P < 0.05; NS P ≥ 0.05 with positive signs indicating significantly higher betas than the base level and negative signs indicating significantly lower betas. bAdjusted for smoking group and age only. cAdjusted for smoking group and sex only.