Table 2

Univariable associations between HLA-B27 and positive family history stratified by geographical region

	HLA-B27+ n=1609	HLA-B27− n=439	OR (95% CI)	P value
Positive family history of axSpA
Total population
Present	518	90	1.84 (1.43 to 2.38)	<0.001
Absent	1087	348	Ref
Per geographical region
Asia	144/487	11/58	4.19 (2.24 to 7.83)	<0.001
Europe and North America	196/658	30/182	2.09 (1.40 to 3.13)	<0.001
Latin America	37/164	3/38	3.95 (1.21 to 12.89)	0.023
Middle East and North Africa	141/300	46/161	0.98 (0.69 to 1.40)	0.917
Positive family history of uveitis
Total population
Present	66	10	1.81 (0.92 to 3.56)	0.084
Absent	1537	422	Ref
Per geographical region
Asia	12/487	0/58	n.a.	n.a.
Europe and North America	28/658	5/182	1.54 (0.59 to 4.01)	0.379
Latin America	6/164	1/38	1.65 (0.20 to 13.72)	0.644
Middle East and North Africa	20/300	4/161	1.37 (0.47 to 4.04)	0.565
Positive family history of ReA
Total population
Present	14	3	1.26 (0.36 to 4.40)	0.719
Absent	1583	427	Ref
Per geographical region
Asia	5/487	0/58	n.a.	n.a.
Europe and North America	5/658	1/182	1.35 (0.16 to 11.58)	0.785
Latin America	2/164	0/38	n.a.	n.a.
Middle East and North Africa	2/300	2/161	0.27 (0.04 to 1.92)	0.191
Positive family history of IBD
Total population
Present	47	27	0.45 (0.28 to 0.74)	0.001
Absent	1551	403	Ref
Per geographical region
Asia	0/487	1/58	n.a.	n.a.
Europe and North America	34/658	17/182	0.52 (0.29 to 0.94)	0.030
Latin America	0/164	3/38	n.a.	n.a.
Middle East and North Africa	13/300	6/161	0.56 (0.21 to 1.49)	0.247
Positive family history of psoriasis
Total population
Present	148	57	0.68 (0.49 to 0.94)	0.020
Absent	1461	382	Ref
Per geographical region
Asia	9/487	0/58	n.a.	n.a.
Europe and North America	98/658	34/182	0.75 (0.50 to 1.13)	0.172
Latin America	13/164	4/38	0.85 (0.28 to 2.62)	0.777
Middle East and North Africa	28/300	19/161	0.39 (0.21 to 0.70)	0.002

axSpA, axial spondyloarthritis; HLA-B27, human leucocyte antigen B27; IBD, inflammatory bowel disease; n.a., not available; ReA, reactive arthritis; Ref, reference category.