Table 2.

Multivariate regression analysis for free and total IGF-I, PAPP-A2, intact and total IGFBP-3, and ratio of free to total IGF-I.

Variable	β	SEB	P value	Adjusted R2
Free IGF-Ia
Age	0.108	0.03	0.0004	0.05
Age2	−0.004	0.001	0.01
Male	−0.076	0.047	0.11
African-American	−0.076	0.024	0.83
BMI Z-score	−0.016	0.026	0.54
Height Z-score	0.064	0.025	0.01
Total IGF-Ia
Age	0.23	0.016	<0.001	0.66
Age2	−0.0056	0.008	<0.0001
Male	−0.194	0.025	<0.0001
African-American	0.129	0.036	0.0003
BMI Z-score	0.048	0.014	0.0005
Height Z-score	0.11	0.013	<0.0001
PAPP-A2a
Age	−0.07	0.004	<0.0001	0.29
Male	−0.032	0.033	0.33
African-American	0.052	0.047	0.27
BMI Z-score	−0.11	0.018	<0.0001
Height Z-score	−0.033	0.018	0.06
Intact IGFBP-3
Age	128	15.4	<0.0001	0.57
Age2	−1.79	0.75	0.02
Male	−15.8	24	0.51
African-American	−112	33.9	0.001
BMI Z-score	94.9	13	<0.0001
Height Z-score	65.4	12.7	<0.0001
Total IGFBP-3
Age	539.6	73.4	<0.0001	0.16
Age2	−28.2	3.58	<0.0001
Male	−1007.8	114.3	<0.0001
African-American	−569.4	161.4	0.0004
BMI Z-score	−80.6	61.9	0.19
Height Z-score	177.6	60.7	0.004
Percentage of free to total IGF-Ia
Age	−0.122	0.03	<0.0001	0.23
Male	0.12	0.05	0.01
African-American	−0.12	0.06	0.07
BMI Z-score	−0.06	0.02	0.01
Height Z-score	−0.04	0.02	0.07

^aThe natural log-transformation was used for statistical analysis of free and total IGF-I, PAPP-A2 and percentage of free to total IGF-I. β, adjusted regression coefficient; SE_β, standard error of the coefficient.