Table 3.

Instrumental Variable Analysis of the Effect of Obesity on Bone Variables

				Women
		Men (n = 1110)		All (n = 1397)		Premenopausal (n = 1015)		Postmenopausal (n = 382)		Total (n = 2507)
Variables	Sites of bones	β ± SE	p	β ± SE	p	β ± SE	p	β ± SE	p	β ± SE	p
BMI
BMC	WB	95.93 ± 27.42	<0.0005	79.60 ± 26.76	0.003	111.33 ± 31.24	<0.0005	−6.65 ± 67.79	0.922	95.52 ± 19.56	<0.0005
	non‐WB	67.59 ± 13.86	<0.0005	26.74 ± 12.04	0.026	42.99 ± 13.51	0.001	−16.5 ± 32.2	0.608	51.4 ± 9.26	<0.0005
	Skull	1.40 ± 63.45	0.982	58.68 ± 53.43	0.272	84.39 ± 60.59	0.164	6.53 ± 113.34	0.954	28.2 ± 40.15	0.482
BA	WB	38.16 ± 13.7	0.0050	40.75 ± 15.61	0.009	57.11 ± 19.08	0.003	−4.29 ± 35.98	0.905	43.03 ± 10.37	<0.0005
	non‐WB	47.22 ± 9.92	<0.0005	27.90 ± 10.67	0.009	41.52 ± 12.42	0.001	−9.15 ± 26.95	0.734	40.79 ± 7.36	<0.0005
	Skull	−0.78 ± 10.4	0.940	4.07 ± 11.2	0.716	10.03 ± 12.03	0.404	−9.15 ± 26.41	0.729	2.39 ± 7.37	0.746
BMD	WB	0.062 ± 0.020	0.0020	0.056 ± 0.024	0.021	0.075 ± 0.023	0.001	0.007 ± 0.072	0.922	0.063 ± 0.016	<0.0005
	non‐WB	0.048 ± 0.015	0.0020	0.014 ± 0.016	0.381	0.026 ± 0.018	0.145	−0.016 ± 0.037	0.661	0.034 ± 0.011	0.002
	Skull	0.058 ± 0.142	0.683	0.225 ± 0.138	0.103	0.269 ± 0.161	0.095	0.113 ± 0.272	0.677	0.120 ± 0.097	0.214
aBMC	WB	0.018 ± 0.016	0.251	0.015 ± 0.023	0.509	0.017 ± 0.021	0.421	0.01 ± 0.065	0.879	0.016 ± 0.013	0.211
	non‐WB	0.004 ± 0.018	0.834	−0.015 ± 0.024	0.529	−0.018 ± 0.026	0.488	−0.003 ± 0.052	0.952	−0.006 ± 0.014	0.642
	Skull	0.054 ± 0.042	0.199	0.103 ± 0.055	0.059	0.094 ± 0.057	0.097	0.136 ± 0.142	0.341	0.065 ± 0.033	0.050
aWC
BMC	WB	156.53 ± 49.65	0.002	3.08 ± 43.13	0.943	−13.78 ± 78.64	0.8610	35.37 ± 54.17	0.514	73.45 ± 34.01	0.031
	non‐WB	57.41 ± 22.99	0.013	24.4 ± 22.3	0.274	50.96 ± 48.3	0.2910	14.87 ± 22.92	0.517	37.05 ± 16.88	0.028
	Skull	−46.58 ± 85.66	0.587	166.65 ± 94.7	0.078	378.26 ± 263.65	0.151	30.2 ± 94.61	0.750	57.17 ± 60.94	0.348
BA	WB	94.36 ± 24.96	<0.0005	−22.94 ± 25.93	0.376	−37.93 ± 53.21	0.4760	−6.35 ± 28.44	0.823	35.54 ± 16.82	0.035
	non‐WB	38.14 ± 15.77	0.0160	16.00 ± 18.53	0.388	29.29 ± 36.46	0.4220	13.02 ± 20.19	0.519	22.72 ± 12.74	0.075
	Skull	−25.34 ± 14.87	0.088	29.6 ± 18.61	0.112	65.42 ± 46.26	0.157	6.16 ± 21.60	0.775	−0.74 ± 10.95	0.946
BMD	WB	0.054 ± 0.032	0.091	0.045 ± 0.043	0.291	0.051 ± 0.0700	0.4670	0.063 ± 0.062	0.311	0.043 ± 0.027	0.107
	non‐WB	0.045 ± 0.024	0.057	0.029 ± 0.028	0.311	0.061 ± 0.063	0.3330	0.017 ± 0.028	0.532	0.036 ± 0.019	0.055
	Skull	0.019 ± 0.192	0.923	0.458 ± 0.256	0.073	1.067 ± 0.742	0.150	0.017 ± 0.226	0.942	0.242 ± 0.153	0.113
aBMC	WB	−0.034 ± 0.021	0.116	0.054 ± 0.037	0.14	0.083 ± 0.076	0.28	0.041 ± 0.042	0.323	0.006 ± 0.019	0.746
	non‐WB	0.011 ± 0.025	0.654	0.017 ± 0.032	0.606	0.041 ± 0.069	0.558	0.005 ± 0.031	0.879	0.018 ± 0.021	0.382
	Skull	0.103 ± 0.062	0.098	0.138 ± 0.084	0.102	0.271 ± 0.209	0.196	0.053 ± 0.083	0.521	0.132 ± 0.054	0.015

Bold values of p are significant.

SE = standard error; BMI = body mass index; BMC = bone mineral content; WB = weight‐bearing bones; non‐WB = non–weight‐bearing bones except for skull; BA = bone area; BMD = bone mineral density; aBMC = area‐adjusted bone mineral content; aWC = waist circumference adjusted for BMI.