Table 1.

^a Baseline characteristics of the normal BMD and the low BMD in all study populations

	Overall (N = 1419)
Characteristics	Normal BMD	Low BMD	P-value
Age (years)	49.03 ± 10.87	59.82 ± 8.59	< 0.0001
Height (cm)	163.08 ± 8.15	158.80 ± 7.66	< 0.0001
Weight (kg)	64.48 ± 11.25	58.91 ± 9.28	< 0.0001
BMI (kg/m2)	24.14 ± 3.11	23.31 ± 2.90	< 0.0001
SBP (mmHg)	124.76 ± 19.16	128.35 ± 19.19	0.0010
DBP (mmHg)	76.60 ± 11.96	76.64 ± 11.66	0.9474
Fracture	102 (10.64%)	81 (17.61%)	0.0002
Hyperthyroidism	20 (2.09%)	13 (2.83%)	0.3863
Hypertension	139 (14.49%)	90 (19.57%)	0.0151
CHD	9 (0.94%)	18 (3.91%)	0.0001
DM	58 (6.05%)	40 (8.70%)	0.0657
Chronic gastrointestinal disease	104 (10.84%)	61 (13.26%)	0.4097
Chronic renal failure	50 (5.21%)	25 (5.43%)	0.8617
Gout	31 (3.23%)	6 (1.30%)	0.0329
Malignant tumor	7 (0.73%)	4 (0.87%)	0.7789
Estrogen drugs	5 (0.52%)	11 (2.39%)	<.0001
Corticosteroids	3 (0.21)	1 (0.22%)	0.7510
Calcium tablet	167 (17.41%)	151 (32.83%)	<.0001
Smoking	233 (24.30%)	87 (18.91%)	0.0231
Drinking	371 (38.69%)	116 (25.22%)	<.0001
Cooking	456 (47.55%)	299 (65.00%)	<.0001
The nature of work			0.0003
sedentary	462 (48.18%)	169 (36.74%)
light activity	455 (47.45%)	268 (58.26%)
manual labor	42 (4.38%)	23 (5.00%)
The main mode of transportation to work			<.0001
working at home	250 (26.07%)	128 (27.83%)
walking	221 (23.04%)	78 (16.69%)
taking buses	172 (17.94%)	197 (42.83%)
driving	316 (32.95%)	57 (12.39%)
Do the household work			<.0001
Never	101 (10.53%)	43 (9.35%)
Occasionally	455 (47.45%)	143 (31.09%)
Often	403 (42.02%)	274 (59.57)
Physical exercise	635 (66.21%)	333 (72.39%)	0.0193

a: Values are Mean ± standard deviation, median (interquartile range) or number (percentage)