POS0975 CLINICAL CHARACTERISTICS OF NONRADIOGRAPHIC AXIAL SPONDYLOARTHRITIS IN ASIAN COUNTRIES COMPARED TO OTHER REGIONS: RESULTS OF THE INTERNATIONAL CROSS-SECTIONAL ASAS-COMOSPA STUDY

Abstract

Background:Clinical characteristics of nonradiographic axial spondyloarthritis (nr-ax-SpA) are highly variable across patients, and may potentially vary across patient populations, particularly due to differing distributions of human leukocyte antigens (HLA) and other genetic factors. The majority of nr-ax-SpA studies have been conducted in Europe, the United States, and small studies are reported from Asia [1].Objectives:To delineate clinical characteristics of patients with nr-ax-SpA in Asian countries in comparison to other areas of the world.Methods:Utilizing the ASAS-COMOSPA data, an international cross-sectional observational study of SpA patients, we analyzed information on demographics, disease characteristics, comorbidities, and risk factors. Patients were classified by region: Asia (China, Japan, Singapore, South Korea, and Taiwan), and non-Asian countries (Europe, Americas, and Africa); patient characteristics, including diagnosis and treatment, were compared.Results:Among 3984 SpA patients included in the study, 1094 were from centers in Asian countries, and 2890 from other regions. 112/780 (14.4%) of axial SpA patients in Asian countries were nr-ax-SpA, substantially less than in other countries (486/1997, 24.3%). Nr-ax-SpA patients in Asian countries compared to nr-ax-SpA in other countries were more likely male (75.9 vs 47.1%), have onset (22.8 vs 27.8 years) and diagnosis (27.2 vs 34.5 years) at younger age, and experience less diagnostic delay (1.88 vs 2.92 years) (Table 1). Nr-ax-SpA patients in Asian countries have higher prevalence of positive HLA-B27 (90.6% vs 61.9%) and fewer peripheral signs such as arthritis, enthesitis, or dactylitis (53.6% vs 66.3%) but have similar rate of extra-articular manifestations (psoriasis, IBD, or uveitis) and co-morbidities. Disease activity, functional impairment, and inflammation on MRI were less in nr-ax-SpA patients in Asian countries. NSAIDs response was higher and use of methotrexate and b-DMARDs were lower among nr-ax-SpA in Asian countries.Conclusion:Among axial SpA patients, substantially lower frequency of nr-ax-SpA was observed in Asian countries compared to other regions of the world. Nr-ax-SpA patients in Asian countries were predominantly male, and had younger disease onset with higher HLA-B27 positivity rate and less peripheral signs, and better response to NSAIDs. These results offer an opportunity to improve both early diagnosis and treatment of nr-ax-SpA patients in Asian countries.Table 1.Characteristics of nonradiographic axial SpA in Asia versus non-Asian regionsVariablesAsianon-Asian regionsp valueN112486Age at disease diagnosis, yrs27.2 [21.1, 39.6]34.5 [27.7, 41.7]<0.001Diagnostic delay, yrs1.88 [0.27, 5.56]2.92 [0.59, 9.58]0.011Male (%)85 (75.9)229 (47.1)<0.001Sacroiliitis on MRI among tested (%)49 (67.1)341 (82.2)0.005HLA B27 positivity among measured (%)96 (90.6)273 (61.9)<0.001Inflammatory Back Pain (%)107 (95.5)478 (98.4)0.076Arthritis, enthesitis, or dactylitis (%)60 (53.6)322 (66.3)0.016Psoriasis (%)12 (10.7)82 (16.9)0.142Uveitis (%)20 (17.9)81 (16.7)0.870Inflammatory bowel disease (%)5 (4.5)27 (5.6)0.817Elevated CRP (%)37 (33.0)213 (43.8)0.048Physician global assessment (0-10)2.0 [1.0, 5.0]2.0 [1.0, 4.0]0.741Patient global assessment (0-10)3.0 [1.0, 6.0]4.0 [2.0, 6.0]0.012ASDAS-CRP1.40 [0.95, 2.08]1.97 [1.21, 2.78]<0.001BASFI0.8 [0.05, 2.65]2.9 [0.8, 5.6]<0.001Good response to NSAIDs (%)80 (71.4)272 (56.0)0.004Methotrexate use (%)18 (16.1)134 (27.6)0.016Biological DMARDs use (%)27 (24.1)191 (39.3)0.004