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

BMC Public Health

Table 4 Multiple logistic regression analysis of odds ratios (OR) for participation in the IDEFICS study versus belonging to the reference population

		Univariate			Multivariate
Coefficients	OR	(95% CI)	p-value	OR	(95% CI )	p-value
Family type^a	2.04	(1.61-2.57)	<0.001	1.75	(1.38-2.23)	<0.001
Number of children in the family^b	1.40	(1.14-1.72)	0.001
Parental origin^c	2.01	(1.56-2.58)	<0.001	1.91	(1.48-2.47)	<0.001
Highest attained education Medium vs Low^d	1.63	(0.94-2.83)	0.966	1.19	(0.68-2.09)	0.436
Highest attained education High vs Low^d	2.63	(1.52-4.54)	<0.001	1.80	(1.02-3.16)	0.001
Disposable income/family (100.000 SEK)^e	1.06	(1.02-1.09)	0.001
Unemployment compensation/family^f	1.41	(1.13-1.75)	0.003
Disability pension/family^f	1.84	(1.29-2.63)	0.001
Social welfare pension/family^f	2.64	(1.69-4.12)	<0.001
Financial study assistance/family^f	1.49	(1.16-1.90)	0.002
Child BMI SDS index	0.96	(0.91-1.02)	0.219

The dependent variable is the odds of family characteristics in the IDEFICS population vs. the reference population (0 = reference population).
^a Reference category = Single parent.
^b Reference category = 1 child (1 vs. 2 or more children).
^c Reference category = Non-Swedish.
^d The ISCED educational levels are low 1–2, medium 3–4, and high 5–6.
^e SEK= the currency of Sweden, the Swedish krona.
^f Reference category = yes.

ISSN: 1471-2458