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Table 3 Subgroup analysis

From: Impact of smoking reduction on lung cancer risk in patients with COPD who smoked fewer thanĀ 30 pack-years: a nationwide population-based cohort study

Ā 

No of cases

(100-person year)

Adjusted HR*

(95% CI)

P for interaction

Age

Ā Ā 

0.77

ā‰¤ 65

Ā Ā Ā 

ā€ƒContinue

54 (0.3)

Reference

Ā 

ā€ƒOver 20% Reducer

17 (0.3)

0.79 (0.45, 1.38)

Ā 

ā€ƒQuit

26 (0.3)

0.77 (0.48, 1.23)

Ā 

>ā€‰65

Ā Ā Ā 

ā€ƒContinue

171 (1.4)

Reference

Ā 

ā€ƒOver 20% Reducer

51 (1.0)

0.72 (0.53, 0.99)

Ā 

ā€ƒQuit

150 (1.1)

0.77 (0.62, 0.97)

Ā 

Sex

Ā Ā 

0.02

Male

Ā Ā Ā 

ā€ƒContinue

210 (0.8)

Reference

Ā 

ā€ƒOver 20% reducer

56 (0.6)

0.67 (0.50, 0.91)

Ā 

ā€ƒQuit

167 (0.8)

0.79 (0.64, 0.98)

Ā 

Female

Ā Ā Ā 

ā€ƒContinue

15 (0.4)

Reference

Ā 

ā€ƒOver 20% reducer

12 (0.8)

1.36 (0.61, 3.01)

Ā 

ā€ƒQuit

9 (0.3)

0.59 (0.25, 1.42)

Ā 

Income

Ā Ā 

0.89

Medical aid

Ā Ā Ā 

ā€ƒContinue

7 (0.3)

Reference

Ā 

ā€ƒOver 20% reducer

3 (0.4)

1.02 (0.21, 5.08)

Ā 

ā€ƒQuit

2 (0.2)

0.07 (0.01, 0.71)

Ā 

ā‰¤ā€‰30th

Ā Ā Ā 

ā€ƒContinue

48 (0.7)

Reference

Ā 

ā€ƒOver 20% reducer

13 (0.5)

0.65 (0.35, 1.22)

Ā 

ā€ƒQuit

36 (0.7)

0.87 (0.56, 1.36)

Ā 

31st ā€“ 70th

Ā Ā Ā 

ā€ƒContinue

85 (0.8)

Reference

Ā 

ā€ƒOver 20% reducer

22 (0.6)

0.63 (0.39, 1.01)

Ā 

ā€ƒQuit

61 (0.7)

0.72 (0.51, 1.01)

Ā 

>ā€‰70th

Ā Ā Ā 

ā€ƒContinue

81 (0.8)

Reference

Ā 

ā€ƒOver 20% reducer

30 (0.9)

0.92 (0.60, 1.41)

Ā 

ā€ƒQuit

75 (0.9)

0.85 (0.61, 1.17)

Ā 

BMI

Ā Ā 

0.89

Underweight

Ā Ā Ā 

ā€ƒContinue

20 (0.9)

Reference

Ā 

ā€ƒOver 20% reducer

8 (0.9)

0.88 (0.38, 2.03)

Ā 

ā€ƒQuit

13 (0.8)

0.69 (0.33, 1.43)

Ā 

Normal

Ā Ā Ā 

ā€ƒContinue

107 (0.9)

Reference

Ā 

ā€ƒOver 20% reducer

32 (0.7)

0.72 (0.48, 1.07)

Ā 

ā€ƒQuit

74 (0.8)

0.74 (0.54, 0.99)

Ā 

Overweight

Ā Ā Ā 

ā€ƒContinue

54 (0.8)

Reference

Ā 

ā€ƒOver 20% reducer

12 (0.5)

0.61 (0.33, 1.16)

Ā 

ā€ƒQuit

51 (0.9)

0.97 (0.66, 1.44)

Ā 

Obesity

Ā Ā Ā 

ā€ƒContinue

44 (0.5)

Reference

Ā 

ā€ƒOver 20% reducer

16 (0.5)

0.93 (0.52, 1.66)

Ā 

ā€ƒQuit

38 (0.5)

0.75 (0.48, 1.17)

Ā 

Smoking status at Exam 1

Ā Ā 

0.45

Light-Moderate

Ā Ā Ā 

ā€ƒContinue

193 (0.8)

Reference

Ā 

ā€ƒOver 20% reducer

58 (0.8)

0.79 (0.58, 1.06)

Ā 

ā€ƒQuit

157 (0.8)

0.78 (0.63, 0.97)

Ā 

Heavy

Ā Ā Ā 

ā€ƒContinue

32 (0.5)

Reference

Ā 

ā€ƒOver 20% reducer

10 (0.3)

0.52 (0.25, 1.07)

Ā 

ā€ƒQuit

19 (0.5)

0.82 (0.45, 1.49)

Ā 

CCIĀ¶

Ā Ā 

0.88

ā‰¤ 1

Ā Ā Ā 

ā€ƒContinue

91 (0.7)

Reference

Ā 

ā€ƒOver 20% reducer

24 (0.5)

0.67 (0.42, 1.06)

Ā 

ā€ƒQuit

57 (0.6)

0.73 (0.52, 1.01)

Ā 

> 1

Ā Ā Ā 

ā€ƒContinue

134 (0.8)

Reference

Ā 

ā€ƒOver 20% reducer

44 (0.7)

0.78 (0.55, 1.10)

Ā 

ā€ƒQuit

119 (0.8)

0.82 (0.63, 1.05)

Ā 

Severe exacerbationĀ¶

Ā Ā 

0.43

No

Ā Ā Ā 

ā€ƒContinue

216 (0.8)

Reference

Ā 

ā€ƒOver 20% reducer

64 (0.6)

0.73 (0.55, 0.97)

Ā 

ā€ƒQuit

154 (0.7)

0.76 (0.61, 0.93)

Ā 

Yes

Ā Ā Ā 

ā€ƒContinue

9 (0.5)

Reference

Ā 

ā€ƒOver 20% reducer

4 (0.5)

0.89 (0.27, 2.99)

Ā 

ā€ƒQuit

22 (0.9)

1.39 (0.61, 3.16)

Ā 
  1. All P for interactions were not statistically significant (Pā€‰>ā€‰0.05), except for sex
  2. * Adjusted for age, sex, BMI, residential area, income, regular physical activity, pack-years (Exam 1), ICS within 1 year of Exam 2, severe exacerbation within 1 year of Exam 2, and comorbidities within 1 year of Exam 2
  3. Ā¶ Variables were assessed within 1 year of Exam 2
  4. BMI, body mass index; ICS, inhaled corticosteroid; COPD, chronic obstructive pulmonary disease; HR, hazard ratio; CI, confidence interval; CCI, Charlson Comorbidity Index
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Respiratory Research

ISSN: 1465-993X

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