Table 4 Analysis of potential factors affecting BMD using univariate logistic regression

Line

0 = Chinese line

47 (54.02%)³

550 (86.34%)

142 (84.02%)

2.57 (0.55–1.34)

1 = American line ^{ref 2}

40 (45.98%)

87 (13.66%)

27 (15.98%)

–

Age, M

1 =  ≤ 12

0 (0)

181 (28.41%)

63 (37.28%)

11.65 (1.97–2.94)

2 = 13–24

2 (2.30%)

304 (47.72%)

63 (37.28%)

7.77 (1.60–2.50)

3 = 25–36

13 (14.94%)

64 (10.05%)

15 (8.88%)

3.98 (0.78–1.98)

4 =  ≥ 37

72 (82.76%)

88 (13.82%)

28 (16.56%)

–

Body Weight, Kg

1 =  ≤ 200

0 (0)

125 (19.62%)

41 (24.26%)

6.78 (1.39–2.44)

2 = 201–250

0 (0)

237 (37.21%)

67 (39.64%)

6.07 (1.32–2.29)

3 = 251–300

43 (49.43%)

206 (32.34%)

39 (23.08%)

2.18 (0.32–1.24)

4 =  ≥ 301

44 (50.57%)

69 (10.83%)

22 (13.02%)

–

Backfat thickness, mm

1 =  ≤ 12

1 (1.15%)

41 (6.44%)

9 (5.33%)

1.15 (− 0.75–1.02)

2 = 13

1 (1.15%)

140 (21.98%)

45 (26.63%)

1.58 (− 0.25–1.17)

3 = 14

8 (9.20%)

162 (25.43%)

51 (30.18%)

1.37 (− 0.39–1.01)

4 = 15

17 (19.54%)

115 (18.05%)

27 (15.98%)

0.78 (− 0.98–0.48)

5 = 16

27 (31.03%)

85 (13.34%)

11 (6.51%)

0.31 (− 1.92–0.39)

6 = 17

9 (10.35%)

43 (6.75%)

5 (2.96%)

0.42 (− 1.75–0.006)

7 = 18

16 (18.39%)

25 (3.93%)

8 (4.73%)

0.25 (− 2.27–0.48)

8 =  ≥ 19

18 (20.69%)

26 (4.08%)

13 (7.69%)

–

Serum Ca, mg/dL

1 =  ≤ 8

7 (8.05%)

59 (9.26%)

30 (17.75%)

1.59 (− 0.041–0.97)

2 = 8–11

65 (74.71%)

420 (65.94%)

96 (56.81%)

0.73 (− 0.65–0.030)

3 =  ≥ 11

15 (17.24%)

158 (24.80%)

43 (25.44%)

–

Serum P, mg/dL

1 =  ≤ 4

42 (48.28%)

125 (19.62%)

26 (15.38%)

0.22 (− 2.10–0.94)

2 = 4–9

45 (51.72%)

459 (72.06%)

122 (72.19%)

0.55 (− 1.11–0.10)

3 =  ≥ 9

0 (0)

53 (8.32%)

21 (12.43%)

–