Assessment of selection bias in a health survey of children and families – the IDEFICS Sweden-study

BMC Public Health

Table 2 Comparison of children’s anthropometric measurements in the IDEFICS and reference populations

Child anthropometric measurements	IDEFICS population	Reference population	p-value
Child anthropometric measurements	(n=1 825)	(n=1 825)
BMI SDS index at age of inclusion^a	0.110 (1.000)	0.169 (0.976)	0.160
	0.085 (−3.548; 4.010)	0.126 (−3.432; 3.671)
	n = 1 644	n = 1 479
BMI SDS at 2.5 years^b	0.135 (0.997)	0.163 (0.984)	0.469
BMI SDS at 2.5 years^b	n = 1 389	n = 1 265	0.469
BMI SDS at 4 years^b	0.063 (0.987)	0.067 (0.986)	0.978
BMI SDS at 4 years^b	n = 1 622	n = 1 471	0.978
BMI SDS at 5.5 years^b	0.080 (1.016)	0.075 (1.009)	0.521
BMI SDS at 5.5 years^b	n = 1 450	n = 1 333	0.521
BMI SDS at 8 years^b	0.191 (1.025)	0.303 (1.040)	0.049
BMI SDS at 8 years^b	n = 1 060	n = 1 002	0.049
BMI categories at 2.5 years
Normal weight and underweight	1 227 (88.4%)	1 096 (86.6%)
Overweight	136 (9.8%)	147 (11.6%)
Obese	25 (1.8%)	22 (1.7%)	0.281
BMI categories at 4 years
Normal weight and underweight	1 443 (89.0%)	1 302 (88.6%)
Overweight	153 (9.4%)	138 (9.4%)
Obese	26 (1.6%)	30 (2.0%)	0.577
BMI categories at 5.5 years
Normal weight and underweight	1 272 (87.7%)	1 150 (86.3%)
Overweight	142 (9.8%)	144 (10.8%)
Obese	36 (2.5%)	39 (2.9%)	0.253
BMI categories at 8 years
Normal weight and underweight	883 (83.2%)	802 (80.0%)
Overweight	147 (13.9%)	155 (15.5%)
Obese	31 (2.9%)	45 (4.5%)	0.033

Data are presented as means with standard deviation (SD), median (min; max), or number and percent (%).
^a BMI SDS index: Body mass index standard deviation score index.
^b BMI SDS: Body mass index standard deviation score.

ISSN: 1471-2458