Table 4.

OR determined with logistic regression for IBS in adoptees with an affected biological or adoptive parent (cohort design)

Risk factors	Ref	Biological parents		Adoptive parents
		Model 1*	Model 2†	Model 3*	Model 4†
IBS	0	1.66 (1.17–2.35)	1.63 (1.14–2.32)	0.77 (0.44–1.34)	0.75 (0.43–1.32)
Year of birth		1.01 (1.00–1.02)	1.01 (1.00–1.02)	1.01 (1.00–1.02)	1.01 (1.00–1.02)
Sex	Male	2.68 (2.29–3.14)	2.61 (2.23–3.06)	2.68 (2.29–3.14)	2.61 (2.23–3.06)
County (region)		1.00 (0.99–1.01)	1.00 (0.99–1.01)	1.00 (0.99–1.01)	1.00 (0.99–1.01)
Education		1.25 (1.13–1.39)	1.16 (1.04–1.29)	1.25 (1.13–1.39)	1.16 (1.04–1.29)

*Univariate model.

†Multivariate model.

IBS, irritable bowel syndrome; Ref, reference.