Undifferentiated spondyloarthritis is more frequently seen in women than in men

[11] Khan MA(2006)Ankylosing spondylitis and undifferentiated spondyloarthritis in Kuwait: a comparison between Arabs and South Asians Clin Rheumatol 25 219-224

[12] Gurler O(2006)Undifferentiated spondyloarthropathy in Chinese patients Arch Med Res 37 384-387

[13] Zochling J(2009)The early disease stage in axial spondylarthritis: results from the German Spondyloarthritis Inception Cohort Arthritis Rheum 60 717-727

[14] Brandt J(2007)Magnetic resonance imaging in ankylosing spondylitis Curr Opin Rheumatol 19 346-352

[15] Braun J(2012)Early spondyloarthritis in multiracial society: differences between gender, race, and disease subgroups with regard to first symptom at presentation, main problem that the disease is causing to patients, and employment status Rheumatol Int 32 1597-1604

[16] Rudwaleit M(2012)Do patients with non-radiographic axial spondylarthritis differ from patients with ankylosing spondylitis? Arthritis Care Res (Hoboken) 64 1415-1422

[17] van der Heijde D(2001)Ankylosing spondylitis and undifferentiated spondyloarthropathies: a clinical review and description of a disease subset with older age at onset Curr Opin Rheumatol 13 280-284

[18] Landewé R(2000)Can some cases of ‘possible’ spondyloarthropathy be classified as ‘definite’ or ‘undifferentiated’ spondyloarthropathy?. Value of criteria for spondyloarthropathies Spanish Spondyloarthropathy Study Group. Joint Bone Spine 67 516-520

[19] Listing J(2006)Low grade radiographic sacroiliitis as prognostic factor in patients with undifferentiated spondyloarthritis fulfilling diagnostic criteria for ankylosing spondylitis throughout follow up Ann Rheum Dis 65 642-646

[20] Akkoc N(2011)Epidemiology of spondyloarthritis in Brazil Am J Med Sci 341 287-288

[11] Khan MA(2006)Ankylosing spondylitis and undifferentiated spondyloarthritis in Kuwait: a comparison between Arabs and South Asians Clin Rheumatol 25 219-224

[12] Gurler O(2006)Undifferentiated spondyloarthropathy in Chinese patients Arch Med Res 37 384-387

[13] Zochling J(2009)The early disease stage in axial spondylarthritis: results from the German Spondyloarthritis Inception Cohort Arthritis Rheum 60 717-727

[14] Brandt J(2007)Magnetic resonance imaging in ankylosing spondylitis Curr Opin Rheumatol 19 346-352

[15] Braun J(2012)Early spondyloarthritis in multiracial society: differences between gender, race, and disease subgroups with regard to first symptom at presentation, main problem that the disease is causing to patients, and employment status Rheumatol Int 32 1597-1604

[16] Rudwaleit M(2012)Do patients with non-radiographic axial spondylarthritis differ from patients with ankylosing spondylitis? Arthritis Care Res (Hoboken) 64 1415-1422

[17] van der Heijde D(2001)Ankylosing spondylitis and undifferentiated spondyloarthropathies: a clinical review and description of a disease subset with older age at onset Curr Opin Rheumatol 13 280-284

[18] Landewé R(2000)Can some cases of ‘possible’ spondyloarthropathy be classified as ‘definite’ or ‘undifferentiated’ spondyloarthropathy?. Value of criteria for spondyloarthropathies Spanish Spondyloarthropathy Study Group. Joint Bone Spine 67 516-520

[19] Listing J(2006)Low grade radiographic sacroiliitis as prognostic factor in patients with undifferentiated spondyloarthritis fulfilling diagnostic criteria for ankylosing spondylitis throughout follow up Ann Rheum Dis 65 642-646

[20] Akkoc N(2011)Epidemiology of spondyloarthritis in Brazil Am J Med Sci 341 287-288