Table 2.

Association between BMI (kg/m²) and lumbar bone mineral density (g/cm²)

	Model 1	Model 2	Model 3
	β (95% CI) P value	β (95% CI) P value	β (95% CI) P value
BMI (kg/m2)	0.005 (0.004, 0.006) < 0.001	0.004 (0.003, 0.006) < 0.001	0.006 (0.003, 0.008) < 0.001
BMI categories
Q1 (30.0–31.8 kg/m2)	Reference	Reference	Reference
Q2 (31.9–34.2 kg/m2)	− 0.007 (− 0.026, 0.011) 0.437	− 0.009 (− 0.027, 0.010) 0.362	− 0.003 (− 0.023, 0.017) 0.774
Q3 (34.3–38.4 kg/m2)	0.003 (− 0.017, 0.022) 0.793	− 0.002 (− 0.021, 0.017) 0.829	− 0.007 (− 0.029, 0.016) 0.568
Q4 (38.5–65.8 kg/m2)	0.054 (0.035, 0.073) < 0.001	0.049 (0.030, 0.068) < 0.001	0.034 (0.002, 0.066) 0.038
Subgroup analysis stratified by sex
Men	0.008 (0.005, 0.010) < 0.001	0.007 (0.005, 0.009) < 0.001	0.013 (0.008, 0.018) < 0.001
Women	0.003 (0.002, 0.004) < 0.001	0.003 (0.002, 0.004) < 0.001	0.003 (0.000, 0.006) 0.044
Subgroup analysis stratified by race/ethnicity
Non-hispanic white	0.005 (0.003, 0.007) < 0.001	0.005 (0.003, 0.007) < 0.001	0.006 (0.001, 0.010) 0.013
Non-hispanic black	0.003 (0.001, 0.005) 0.004	0.004 (0.001, 0.006) 0.003	0.008 (0.003, 0.013) 0.002
Mexican American	0.005 (0.002, 0.008) < 0.001	0.005 (0.002, 0.008) < 0.001	0.006 (0.000, 0.012) 0.037
Other race/ethnicity	0.002 (− 0.001, 0.004) 0.171	0.003 (− 0.000, 0.005) 0.056	0.001 (− 0.004, 0.007) 0.598
Subgroup analysis stratified by age
40–49 years	0.005 (0.004, 0.007) < 0.001	0.004 (0.002, 0.006) < 0.001	0.008 (0.004, 0.011) < 0.001
50–59 years	0.004 (0.002, 0.006) < 0.001	0.005 (0.003, 0.006) < 0.001	0.004 (0.001, 0.008) 0.021

Model 1: no covariates were adjusted. Model 2: age, sex, and race/ethnicity were adjusted. Model 3: age, sex, and race/ethnicity, level of education, poverty to income ratio, vigorous recreational activities, smoking behavior, waist circumference, blood urea nitrogen, total protein, serum glucose, cholesterol, phosphorus, and total calcium were adjusted