Table 1

Demographic data and clinical features of 363 axSpA probands by radiographic status of sacroiliac joints and HLA-B27 status of men and women

ProbandsTotal (n)Age, 1985, mean (SD)CIBP (%)Grade of single SI joint, mean (SE)Male:female ratio
axSpA total363*44.2 (11.1)72.82.7 (0.07)2.18
 Male24945.2 (11.7)74.53.0 (0.07)
 Female11442.1 (9.4)69.02.1 (0.12)
Radiographic axSpA (AS)27344.6 (11.4)73.43.3 (0.04)2.96
 Male20445.6 (11.7)75.73.4 (0.05)
 Female6941.8 (10.1)66.73.0 (0.08)
Non-radiographic axSpA8742.9 (10.1)69.80.9 (0.07)0.98
 Male4342.9 (11.9)67.41.0 (0.10)
 Female4442.9 (8.1)72.10.8 (0.09)
HLA-B27(+) axSpA30844.0 (11.1)72.92.9 (0.06)2.46
 Male21945.2 (11.5)74.73.1 (0.07)
 Female8941.1 (9.5)67.42.5 (0.12)
AS24744.6 (11.6)73.13.3 (0.05)2.98
 Male18545.7 (11.8)75.43.4 (0.05)
 Female6241.3 (10.2)66.13.0 (0.09)
nr-axSpA5841.7 (8.5)69.01.1 (0.08)1.23
 Male3242.3 (9.4)68.81.0 (0.11)
 Female2641.0 (7.4)69.21.1 (0.11)
HLA-B27(−) axial axSpA5046.1 (11.5)69.41.7 (0.21)1.08
 Male2646.3 (14.0)73.12.3 (0.29)
 Female2446.0 (8.4)77.10.9 (0.23)
AS2246.9 (10.1)72.73.1 (0.18)2.67
 Male1646.7 (11.0)75.03.3 (0.22)
 Female647.3 (8.4)66.72.7 (0.25)
nr-axSpA2845.6 (12.7)74.10.5 (0.10)0.56
 Male1045.6 (18.5)70.00.8 (0.24)
 Female1845.6 (8.6)75.50.3 (0.08)
  • The prevalence of CIBP by the Calin criteria and the mean single SI joint grade are provided at the group level.

  • *Unknown radiographic status: 3 probands; unknown HLA-B27 status: 5 probands, including 1 nr-axSpA proband.

  • AS, ankylosing spondylitis; axSpA, axial spondyloarthritis; CIBP, chronic inflammatory back pain; nr-axSpA, non-radiographic axial spondyloarthritis.