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Table 1 Characteristics of statin and metformin users

From: Independent and joint cross-sectional associations of statin and metformin use with mammographic breast density

   

Statin use

Metformin use

Total

Ever users

Never users

 

Ever users

Never users

 

n

%

n

%

n

%

 

n

%

n

%

Total (row percent)

770

100.0

209

27.1

561

72.9

 

102

13.2

668

86.8

 

Medication use

 Metformin ever

102

13.25

69

33.01

33

5.88

**

102

100.0

0

0.00

 

 Statin ever

209

27.14

209

100.0

0

0.00

 

69

67.65

140

20.96

**

 Insulin ever

31

4.03

20

9.57

11

1.96

**

16

15.69

15

2.25

**

 Hormone replacement therapy ever

32

4.16

10

4.78

22

3.92

 

5

4.90

27

4.04

 

 Aspirin ever

159

20.65

82

39.23

77

13.73

**

45

44.12

114

17.07

**

 Anti-hypertension medications ever

294

38.18

133

63.64

161

28.70

**

69

67.65

225

33.68

**

Demographic and medical factors

 Age

  40 to < 45

107

13.90

8

3.83

99

17.65

**

3

2.94

104

15.57

**

  45 to < 50

170

22.08

22

10.53

148

26.38

 

11

10.78

159

23.80

 

  50 to < 55

218

28.31

48

22.97

170

30.30

 

33

32.35

185

27.69

 

  55–61

275

35.71

131

62.68

144

25.67

 

55

53.92

220

32.93

 

  Mean [SD]

51.96 [5.63]

55.11 [4.64]

50.78 [5.52]

**

54.64 [4.38]

51.55 [5.69]

**

 Education

  High school or less

359

46.62

114

54.55

245

43.67

*

63

61.76

296

44.31

**

  Some college

179

23.25

48

22.97

131

23.35

 

20

19.61

159

23.80

 

  At least Bachelor’s

232

30.13

47

22.49

185

3298

 

19

18.63

213

31.89

 

 Race/ethnicity

  Hispanic

604

78.44

176

84.21

428

76.29

*

81

79.41

523

78.29

 

  Non-Hispanic white

60

7.79

8

3.83

52

9.27

 

2

1.96

58

8.68

 

  Non-Hispanic black

88

11.43

20

9.57

68

12.12

 

16

15.69

72

10.78

 

  Non-Hispanic, Asian, or other race

18

2.34

5

2.39

13

2.32

 

3

2.94

15

2.25

 

 Diabetes

  Any

160

20.78

86

41.15

74

13.19

**

94

92.16

66

9.88

**

  Type 1

12

1.56

8

3.83

4

0.71

**

9

8.82

3

0.45

**

  Type 2

100

12.99

68

32.54

32

5.70

**

82

80.39

18

2.69

**

  Gestational

72

9.35

27

12.92

45

8.02

*

23

22.55

49

7.34

**

 BMI

  18.5 to < 25

134

17.40

26

12.44

108

19.25

*

11

10.78

123

18.41

**

  25 to < 30

247

32.08

62

29.67

185

32.98

 

19

18.63

228

34.13

 

  30 to < 35

215

27.92

65

31.10

150

26.74

 

37

36.27

178

26.65

 

  ≥ 35

174

22.60

56

26.79

118

21.03

 

35

34.31

139

20.81

 

  Mean [SD]

30.91 [6.56]

31.80 [6.27]

30.58 [6.64]

*

33.67 [6.66]

30.49 [5.69]

**

Reproductive history

 Age at menarche

  < 12

204

26.49

45

21.53

159

28.34

 

26

25.49

178

26.65

 

  12

138

17.92

37

17.70

101

18.00

 

20

19.61

118

17.66

 

  13

167

21.69

52

24.88

115

20.50

 

26

25.49

141

21.11

 

  > 14

258

33.51

73

34.93

185

32.98

 

29

28.43

229

34.28

 

  Missing

3

0.39

2

0.96

1

0.18

 

1

0.98

2

0.30

 

 Parity

  Nulliparous

101

13.12

27

12.92

74

13.19

 

11

10.78

90

13.47

 

  1–2 children

368

47.79

99

47.37

269

47.95

 

48

47.06

320

47.90

 

  3 or more children

301

39.09

83

39.71

218

38.86

 

43

42.16

258

38.62

 

 Age at first live birth

  Nulliparous

101

13.12

27

12.92

74

13.19

 

11

10.78

90

13.47

 

  < 25 years old

400

51.95

114

54.55

286

50.98

 

63

61.76

337

50.45

 

  25 to < 35 years old

212

27.53

55

26.32

157

27.99

 

23

22.55

189

28.29

 

  > 35 years old

57

7.40

13

6.22

44

7.84

 

5

4.90

52

7.78

 

Breast cancer risk factors

 Post-menopause

455

59.09

179

85.65

276

49.20

**

78

76.47

377

56.44

**

 First-degree family history of breast cancer

95

12.34

23

11.00

72

12.83

 

15

14.71

80

11.98

 

 Age at menopause, mean [SD]

46.39 [6.30]

45.77 [6.60]

46.78 [6.09]

 

45.63 [6.91]

46.54 [6.18]

 
  1. Used chi-squared or Fisher’s exact test for categorical variables and two-sample t test for continuous; missing were excluded
  2. p value comparing ever to never users denoted < 0.05 (*) or < 0.01 (**)