Associations between serum levels of insulin-like growth factor-I and bone mineral acquisition in pubertal children: a 3-year follow-up study in Hamamatsu, Japan

Table 1 Characteristics of the study population and dropout population

	Study population							Dropout population
	Baseline			Follow-up		^aBaseline vs follow-up		Baseline		^bStudy vs dropout populations
	Boys, N = 121	Girls, N=133	^bBoys vs girls	Boys, N = 121	Girls, N = 133	Boys	Girls	Boys, N = 81	Girls, N = 73	Boys	Girls
Age (years)	11.2 ± 0.3	11.2 ± 0.3	ns	14.2 ± 0.3	14.2 ± 0.3	< 0.001	< 0.001	11.2 ± 0.3	11.2 ± 0.3	ns	ns
Height (cm)	141 ± 6	143 ± 7	0.007	162 ± 6	155 ± 5	< 0.001	< 0.001	142 ± 6	143 ± 7	ns	ns
Weight (kg)	34.7 ± 7.4	35.1 ± 5.9	ns	49.9 ± 8.4	47.0 ± 5.8	< 0.001	< 0.001	35.4 ± 7.1	35.5 ± 8.7	ns	ns
TBLH BMC (g)	644 ± 140	700 ± 162	0.003	1143 ± 251	1044 ± 180	< 0.001	< 0.001	656 ± 121	690 ± 178	ns	ns
TB bone area (cm²)	1288 ± 174	1336 ± 186	0.036	1789 ± 211	1680 ± 153	< 0.001	< 0.001	1305 ± 155	1329 ± 195	ns	ns
TBLH aBMD (g/cm²)	0.609 ± 0.040	0.624 ± 0.050	0.005	0.739 ± 0.074	0.720 ± 0.062	< 0.001	< 0.001	0.613 ± 0.037	0.618 ± 0.057	ns	ns
TB BMAD (g/cm³)	0.081 ± 0.008	0.080 ± 0.006	ns	0.075 ± 0.004	0.078 ± 0.005	< 0.001	0.003	0.081 ± 0.007	0.080 ± 0.007	ns	ns
25-hydroxyvitamin D (ng/mL)	34.3 ± 7.8	29.6 ± 7.7	< 0.001
IGF-I (ng/mL)	198 ± 80	281 ± 81	< 0.001
Sedentary behavior (media use), N (%)
< 1 h/day	29 (24)	33 (25)	ns
≥1, < 2 h/day	54 (45)	63 (47)
≥ 2, < 3 h/day	20 (17)	29 (22)
≥ 3, < 4 h/day	11 (9)	6 (5)
≥ 4 h/day	7 (6)	2 (2)
Pubic hair appearance, N (%)
<Grade 5	0 (0)	10 (8)	< 0.001
Grade 5	8 (7)	36 (27)
No appearance	113 (93)	87 (65)

N number, ns not significant, TBLH total body less head, BMC bone mineral content, TB total body, aBMD areal bone mineral density,
BMAD bone mineral apparent density as an estimate of volumetric bone mineral density, IGF-I insulin-like growth factor-I
Values represent mean ± SD or N (%)
^aPaired t test was used to assess the difference between baseline and follow-up surveys
^bP value calculated with unpaired t test or Mann-Whitney U test. P < 0.05 was considered statistically significant

ISSN: 1880-6805