Clinical Characteristics of Patients with Spondyloarthritis in Japan in Comparison with Other Regions of the World

Abstract

Objective.To delineate clinical characteristics of patients with spondyloarthritis (SpA) in Japan in comparison to other areas of the world.Methods.Using the ASAS-COMOSPA (Assessment of Spondyloarthritis international Society–COMOrbidities in SPondyloArthritis) data, an international cross-sectional observational study of patients with SpA, we analyzed information on demographics, disease characteristics, comorbidities, and risk factors. Patients were classified by region: Japan, other Asian countries (China, Singapore, South Korea, Taiwan), and non-Asian countries (Europe, the Americas, Africa). Patient characteristics, including diagnosis and treatment, were compared.Results.Among 3984 patients included in the study, 161 were from centers in Japan, 933 from other Asian countries, and 2890 from other regions. Of patients with SpA in Japan, 42 (26.1%) had peripheral SpA, substantially more than in other countries. This trend was explained by the predominance of psoriatic arthritis (PsA) among Japanese patients with SpA. In contrast to the relatively low number in Japan, 54% of patients from other Asian countries had pure axial SpA (axSpA) without peripheral features. HLA-B27 testing, considered an integral part of the classification of axSpA, was performed in only 63.6% of Japanese patients with axSpA. More than half of Japanese patients with axSpA were classified using imaging criteria.Conclusion.In our study, there was a more substantial number of peripheral SpA cases observed in Japan compared to other parts of Asia and other regions of the world. Aside from ethnic differences, increasing recognition of PsA in Japan, as well as a potential underdiagnosis of axSpA due to the insufficient use of HLA-B27 testing, may partly explain regional discrepancies.

Do geography and ethnicity play a role in juvenile Spondyloarthritis? A multi-center binational retrospective study

“…Most Israeli patients presented to the rheumatology clinic with axial symptoms rather than peripheral symptoms (including enthesitis). Peripheral symptoms of arthritis and enthesitis were the dominant presentation of the US group and were comparable with other reports [10][11][12][17][18][19][20][21]. These observations are supported by the significantly higher percentage of sacroiliitis on MRI upon presentation in the Israeli versus the US cohort (96.7% vs 29.7%), which were validated by the inter-center comparison, with an excellent level of agreement between the reading radiologists in the two countries.…”

“…Additional cohorts of children with ERA from France [17] and India [18] revealed that most patients present with peripheral, rather than axial, symptoms. A recent Japanese study which compared Japanese, Asian and non-Asians adult patients with SpA demonstrated differences in the distribution of peripheral SpA, axial SpA and HLA B27 among these populations, which may indicate that the presentation of the disease is essentially affected by ethnic and environmental factors [20]. In light of the above, the lack of peripheral arthritis and enthesitis in most of our Israeli cohort may be attributed to genetic variations among the different ethnic populations in Israel [22].…”

Non-radiographic versus radiographic axSpA: what’s in a name?

“…These differences can be related to geographical distribution [ 9 ] and are probably driven by the prevalence of HLA-B27, which can be as high as 53% in a tribe in Papua Guinea [ 10 ]. The question remains whether patients in areas with a low prevalence of HLA-B27 are underdiagnosed whilst axSpA might be driven by other genetic factors [ 11 ].…”

Treatment patterns and health care resource utilization among Japanese patients with ankylosing spondylitis: A hospital claims database analysis

“…In Japan, spondyloarthritis is relatively uncommon, with an estimated prevalence of 9.5 per 100,000 person-years [1]. However, the current diagnosis rate for spondyloarthritis has been increasing and suggests spondyloarthritis has historically been both underdiagnosed and misdiagnosed in Japan [2]. The difficulty in accurately diagnosing this condition could be due to a lack of information on clinical characteristics of spondyloarthritis in Japanese patients [2].…”