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Table 3 Effect of smoking on menopause among postmenopausal women (KNHANES, 2007–2014)

From: Factors associated with menstrual cycle irregularity and menopause

Variables

Early menopause (< 50 years)

Late menopause (≥50 years)

Logistic regression for early menopause (< 50 years)a

Linear regression for menopausal age (categorical variable)a

Linear regression for menopausal age (continuous variable)a

n

%

n

%

OR

95% CI

β

SE

p-value

β

SE

p-value

(mean)

(SD)

(mean)

(SD)

Total

4930

45.9

5767

54.1

         

Current age, mean (SD)

64.5

0.2

62.8

0.2

         

Average menopausal age, mean (SD)

45.6

0.1

52.5

0.0

         

Smoking status

 Non-smoker

4447

90.6

5343

93.6

1.00

  

1.000

     

 Ex-smoker

172

3.7

160

2.9

1.34

1.02

1.77

−0.615

0.365

0.093

   

 Current smoker

236

5.7

175

3.5

1.68

1.30

2.17

−1.137

0.283

<.0001

   

 Total

4855

100.0

5678

100.0

         

Cigarettes per day

 Non-smoker

4447

92.3

5343

95.1

1.00

  

1.000

     

 < 20 cigarettes

268

6.1

205

3.9

1.61

1.26

2.07

−1.104

0.302

0.000

   

 ≥ 20 cigarettes

69

1.5

55

1.0

1.53

1.00

2.33

−0.486

0.444

0.274

   

 Total

4784

100.0

5603

100.0

      

−0.038

0.019

0.046

Age at smoking initiationb

 Non-smoker

3409

89.9

3993

93.1

1.00

  

1.000

     

 < 20 years

36

1.2

15

0.4

2.93

1.45

5.90

−1.438

0.461

0.002

   

 ≥ 20 years

298

8.9

246

6.4

1.43

1.13

1.82

−0.827

0.293

0.005

   

 Total

3743

100.0

4254

100.0

      

−0.004

0.001

<.0001

Pack-year (total)b

 Non-smoker

3409

90.2

3993

93.4

1.00

        

 Below or equal to the median (≤9.8 pack-years)

153

4.9

175

3.4

1.50

1.11

2.01

−0.773

0.342

0.024

   

 Above the median (>9.8 pack-years)

172

4.9

78

3.3

1.57

1.17

2.09

−1.037

0.389

0.008

   

 Total

3734

100.0

4246

100.0

      

−0.025

0.015

0.103

Pack-year (before menopause)b

 Non-smoker

3409

92.0

3993

93.7

1.00

  

1.000

     

 Below or equal to the median (≤5 pack-years)

133

4.0

107

2.7

1.54

1.11

2.13

−1.076

0.370

0.004

   

 Above the median (>5 pack-years)

123

4.0

131

3.6

1.14

0.83

1.57

0.417

0.340

0.220

   

 Total

3665

100.0

4231

100.0

      

0.035

0.020

0.077

  1. OR odds ratios, CI confidence interval; a Univariate model  b Excluded KNHANES 2013-2014 because age at smoking initiation was not surveyed