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 regions Variables Asia non-Asian regions p value N 112 486 Age at disease diagnosis, yrs 27.2 [21.1, 39.6] 34.5 [27.7, 41.7] <0.001 Diagnostic delay, yrs 1.88 [0.27, 5.56] 2.92 [0.59, 9.58] 0.011 Male (%) 85 (75.9) 229 (47.1) <0.001 Sacroiliitis on MRI among tested (%) 49 (67.1) 341 (82.2) 0.005 HLA B27 positivity among measured (%) 96 (90.6) 273 (61.9) <0.001 Inflammatory Back Pain (%) 107 (95.5) 478 (98.4) 0.076 Arthritis, enthesitis, or dactylitis (%) 60 (53.6) 322 (66.3) 0.016 Psoriasis (%) 12 (10.7) 82 (16.9) 0.142 Uveitis (%) 20 (17.9) 81 (16.7) 0.870 Inflammatory bowel disease (%) 5 (4.5) 27 (5.6) 0.817 Elevated CRP (%) 37 (33.0) 213 (43.8) 0.048 Physician global assessment (0-10) 2.0 [1.0, 5.0] 2.0 [1.0, 4.0] 0.741 Patient global assessment (0-10) 3.0 [1.0, 6.0] 4.0 [2.0, 6.0] 0.012 ASDAS-CRP 1.40 [0.95, 2.08] 1.97 [1.21, 2.78] <0.001 BASFI 0.8 [0.05, 2.65] 2.9 [0.8, 5.6] <0.001 Good response to NSAIDs (%) 80 (71.4) 272 (56.0) 0.004 Methotrexate use (%) 18 (16.1) 134 (27.6) 0.016 Biological DMARDs use (%) 27 (24.1) 191 (39.3) 0.004 References: [1]López-Medina C, Ramiro S, van der Heijde D, et al. Characteristics and burden of disease in patients with radiographic and non-radiographic axial Spondyloarthritis: a comparison by systematic literature review and meta-analysis. RMD Open. 2019 Nov 21;5(2): e001108. Acknowledgements: This study was conducted under the umbrella of the International Society for Spondyloarthritis Assessment (ASAS) and COMOSPA study was supported by unrestricted grants from Pfizer, AbbVie and UCB. Disclosure of Interests: Keisuke Ono: None declared, Mitsumasa Kishimoto Speakers bureau: AbbVie, Amgen-Astellas BioPharma, Asahi-Kasei Pharma, Astellas, Ayumi Pharma, BMS, Chugai, Daiichi-Sankyo, Eisai, Eli Lilly, Gilead, Janssen, Kyowa Kirin, Novartis, Ono Pharma, Pfizer, Tanabe-M