Table 3.

Multivariable models assessing the effect of HLA-B27 and gender on age at onset of axial symptoms

Variable	Multivariable linear regression
	β (95% CI)	P-value
Total study population (N = 2063)
HLA-B27
Negative	Ref.
Positive	−4.35 (−5.45, −3.25)	<0.001
Gender
Female	Ref.
Male	−1.71 (−2.69, −0.74)	0.001
Asia (n = 525)
HLA-B27
Negative	Ref.
Positive	−3.68 (−6.44, −0.92)	0.009
Gender
Female	Ref.
Male	−2.23 (−4.34, −0.11)	0.039
Europe and North America (n = 862)
HLA-B27
Negative	Ref.
Positive	−5.18 (−6.88, −3.48)	<0.001
Gender
Female	Ref.
Male	−0.92 (−2.38, 0.53)	0.215
Latin America (n = 195)
HLA-B27
Negative	Ref.
Positive	−7.30 (−11.59, −3.00)	0.001
Gender
Female	Ref.
Male	−3.44 (−7.11, 0.23)	0.066
Middle East and North Africa (n = 481)
HLA-B27
Negative	Ref.
Positive	−2.44 (−4.36, −0.53)	0.013
Gender
Female	Ref.
Male	−1.58 (−3.50, 0.34)	0.106

Statistically significant associations are in bold.