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Table 1 Weighted characteristics of the study population based on age at menarche

From: Association between age at menarche and bone mineral density in postmenopausal women

Characteristics

Age at menarche (years)

P value

≤ 12 (n = 570)

13–15 (n = 538)

≥ 16 (n = 87)

Age (years), mean (95% CI)

53.02 (52.45, 53.58)

53.77 (53.26, 54.27)

52.30 (51.06, 53.55)

0.095

Years since menopause (years), mean (95% CI)

8.68 (7.88, 9.48)

7.77 (6.99, 8.55)

9.03 (7.38, 10.68)

0.088

Body mass index (kg/m2), mean (95% CI)

30.83 (29.97, 31.68)

29.23 (28.21, 30.24)

27.89 (26.36, 29.41)

< 0.001

Lumbar spine BMD (g/cm2), mean (95% CI)

1.00 (0.98, 1.02)

0.98 (0.96, 1.00)

0.92 (0.89, 0.95)

< 0.001

Race, percent (95% CI)

   

0.136

 Non-Hispanic white

67.53 (61.38, 73.14)

64.66 (58.13, 70.70)

57.01 (42.03, 70.81)

 

 Non-Hispanic black

12.64 (9.77, 16.21)

13.82 (10.54, 17.91)

18.44 (11.48, 28.28)

 

 Mexican American

7.39 (5.28, 10.25)

6.22 (4.35, 8.81)

3.23 (1.24, 8.16)

 

 Other race

12.43 (9.46, 16.18)

15.30 (12.36, 18.78)

21.32 (12.52, 33.90)

 

Education level, percent (95% CI)

   

0.586

 Less than high school

12.05 (8.72, 16.41)

13.30 (9.64, 18.07)

14.10 (6.72, 27.20)

 

 High school

26.72 (22.36, 31.58)

22.31 (16.98, 28.74)

30.89 (17.77, 48.03)

 

 More than high school

61.24 (54.70, 67.39)

64.39 (56.84, 71.29)

55.01 (38.36, 70.61)

 

Family PIR, percent (95% CI)

   

0.269

 < 1.3

16.59 (13.21, 20.63)

18.28 (13.72, 23.94)

16.30 (8.63, 28.65)

 

 1.3–3.5

31.51 (26.93, 36.48)

25.27 (21.23, 29.78)

41.44 (25.71, 59.13)

 

 ≥ 3.5

45.05 (38.87, 51.39)

49.76 (42.18, 57.36)

38.34 (23.71, 55.43)

 

 Missing

6.85 (4.56, 10.17)

6.69 (4.36, 10.13)

3.93 (1.57, 9.52)

 

Total calcium (mmol/L), percent (95% CI)

   

0.003

 T1 (1.900–2.300)

33.63 (28.74, 38.88)

23.74 (19.22, 28.94)

30.13 (18.63, 44.83)

 

 T2 (2.301–2.375)

33.94 (28.93, 39.34)

38.41 (33.76, 43.28)

19.12 (11.32, 30.44)

 

 T3 (2.376–2.750)

30.05 (24.95, 35.70)

34.39 (28.92, 40.32)

41.73 (26.97, 58.15)

 

 Missing

2.38 (1.15, 4.87)

3.45 (1.61, 7.24)

9.01 (3.43, 21.65)

 

Serum phosphorus (mmol/L), percent (95% CI)

   

0.070

 T1 (0.743–1.130)

24.48 (20.86, 28.50)

32.16 (26.08, 38.91)

22.51 (12.88, 36.34)

 

 T2 (1.131–1.259)

34.16 (28.19, 40.68)

26.62 (21.02, 33.10)

37.36 (21.93, 55.88)

 

 T3 (1.260–1.905)

39.05 (33.43, 44.98)

37.76 (31.72, 44.21)

31.11 (17.54, 48.95)

 

 Missing

2.31 (1.10, 4.79)

3.45 (1.61, 7.24)

9.01 (3.43, 21.65)

 

Smoking behavior, percent (95% CI)

   

0.749

 Never

56.92 (51.34, 62.34)

57.68 (50.46, 64.59)

60.74 (43.71, 75.50)

 

 Former

19.64 (15.39, 24.72)

21.58 (16.69, 27.43)

24.43 (12.36, 42.56)

 

 Current

23.44 (18.74, 28.90)

20.74 (16.35, 25.95)

14.83 (5.68, 33.48)

 

Age started smoking, mean (95% CI)

18.21 (17.17, 19.25)

18.17 (17.26, 19.08)

19.20 (16.13, 22.26)

0.776

Alcohol consumption, percent (95% CI)

   

0.584

 Non-drinker

14.68 (11.26, 18.92)

14.91 (11.37, 19.30)

27.02 (15.04, 43.64)

 

 Moderate drinker

34.51 (29.39, 40.02)

34.27 (27.28, 42.02)

23.86 (12.31, 41.14)

 

 Heavy drinker

39.54 (33.96, 45.40)

37.90 (31.52, 44.71)

36.88 (22.48, 54.07)

 

 Missing

11.27 (8.33, 15.08)

12.93 (9.20, 17.86)

12.24 (4.01, 31.76)

 

Parity, percent (95% CI)

   

0.026

 0–1

16.78 (12.61, 21.99)

19.08 (15.12, 23.78)

22.38 (10.67, 41.04)

 

 2–3

62.66 (58.13, 66.97)

49.65 (44.39, 54.92)

52.05 (36.58, 67.13)

 

 ≥ 4

9.79 (7.56, 12.60)

14.52 (10.96, 18.99)

8.30 (3.49, 18.45)

 

 Missing

10.77 (7.27, 15.67)

16.75 (12.01, 22.88)

17.28 (7.53, 34.90)

 

Female hormone use, percent (95% CI)

28.67 (23.66, 34.26)

26.01 (20.79, 32.00)

25.60 (14.02, 42.05)

0.750

Vigorous activities, percent (95% CI)

29.65 (24.72, 35.10)

25.68 (20.64, 31.46)

32.53 (17.51, 52.28)

0.525

Moderate activities, percent (95% CI)

60.75 (53.61, 67.47)

67.11 (61.76, 72.06)

64.24 (47.20, 78.32)

0.290

Arthritis, percent (95% CI)

40.67 (35.38, 46.19)

36.13 (29.39, 43.46)

27.43 (15.60, 43.61)

0.177

Thyroid disease, percent (95% CI)

22.76 (18.59, 27.56)

16.11 (12.08, 21.16)

25.12 (12.19, 44.76)

0.129

Liver disease, percent (95% CI)

3.60 (2.35, 5.47)

5.93 (3.13, 10.95)

9.66 (2.81, 28.34)

0.218

Kidney disease, percent (95% CI)

2.55 (1.25, 5.15)

2.83 (1.21, 6.49)

1.26 (0.26, 5.81)

0.782

Diabetes, percent (95% CI)

11.81 (8.37, 16.42)

10.59 (7.30, 15.12)

4.72 (1.94, 11.04)

0.496

  1. CI confidence interval, BMD bone mineral density, PIR poverty income ratio, T tertile