POS1411 EARLY IDENTIFICATION OF AXIAL SPONDYLOARTHRITIS IN A MULTI-ETHNIC ASIAN POPULATION
Authors: L. Xiang, W. Fong, A. Low, Y. Y. Leung, M. Gandhi, X. Xin, E. Uy, L. Hamilton, J. Thumboo
Journal: Annals of the Rheumatic Diseases (2021)

Background: To facilitate earlier diagnosis of spondyloarthritis (SpA), we have previously cross-culturally adapted a self-administered screening questionnaire. Objectives: We aimed to improve the sensitivity of this questionnaire as a screening tool by comparing various scoring methods. Methods: Subjects newly referred to a rheumatology clinic self-administered the questionnaire before seeing a rheumatologist. Identification of axial SpA by the questionnaire using original scoring (Method A) and scoring based on Assessment of SpondyloArthritis International Society (ASAS) inflammatory back pain (IBP) criteria (Method B), ASAS referral criteria (Method C), ASAS classification criteria (Method D) and a combination of ASAS referral and classification criteria (Method E) were compared to classification by the ASAS classification criteria and diagnosis by rheumatologist. Since Methods B-E were based on SpA features, we compared self-reported vs rheumatologist-documented features in subjects with axial SpA. Results: Of 1418 subjects (age: 54 ± 14 years, female: 73%), 39 were classified as axial SpA cases by classification criteria. Methods A-E yielded sensitivities of 39%, 72%, 67%, 49% and 85%, respectively, among patients newly referred to the rheumatology clinic (Table 1). Rheumatologist-documented clinical SpA features exceeded self-report for IBP (62 vs 44%) and uveitis (15 vs 5%). The reverse was true for arthritis (21 vs 80%), enthesitis (28 vs 33%), dactylitis (3 vs 18%), good response to NSAIDs (33 vs 41%) and family history for SpA (5 vs 10%). Table 1. Performance of the five scoring methods for the cross-culturally adapted Hamilton axial SpA questionnaire. Scoring method Sensitivity (95% confidence interval) Specificity (95% confidence interval) Positive predictive value (95% confidence interval) Negative predictive value (95% confidence interval) Method A 38.5 (23.4 – 55.4) 93.7 (92.3 – 94.9) 14.7 (8.5 – 23.1) 98.2 (97.3 – 98.8) Method B 71.8 (55.1 – 85.0) 73.1 (70.7 – 75.4) 7.0 (4.7 – 10.0) 98.9 (98.1 – 99.5) Method C 66.7 (49.8 – 80.9) 77.8 (75.5 – 80.0) 7.8 (5.2 – 11.3) 98.8 (98.0 – 99.4) Method D 48.7 (32.4 – 65.2) 74.9 (72.5 – 77.2) 5.2 (3.2 – 8.0) 98.1 (97.1 – 98.8) Method E 84.6 (69.5 – 94.1) 37.2 (34.6 – 39.8) 3.7 (2.5 – 5.1) 98.8 (97.5 – 99.6) Method A: the original scoring defined by the questionnaire developers; Method B: a scoring based on the ASAS IBP criteria; Method C: a scoring based on the ASAS referral criteria; Method D: a scoring based on the ASAS classification criteria for axial and peripheral SpA; Method E: a scoring based on a combination of the ASAS referral and classification criteria. Conclusion: A self-administered questionnaire scored based on a combination of ASAS referral and classification criteria achieved high sensitivity in identifying axial SpA in subjects referred to a rheumatology clinic. This supports its evaluation as a screening tool for axial SpA in the general population. References: [1]Xiang L, Teo EPS, Low AHL, Leung YY, Fong W, Xin X, et al. Cross-cultural adaptation of the Hamilton axial spondyloarthritis questionnaire and development of a Chinese version in a multi-ethnic Asian population. Int J Rheum Dis. 2019;22(9):1652-60. [2]Sieper J, Rudwaleit M, Baraliakos X, Brandt J, Braun J, Burgos-Vargas R, et al. The Assessment of SpondyloArthritis international Society (ASAS) handbook: a guide to assess spondyloarthritis. Annals of the rheumatic diseases. 2009;68 Suppl 2:ii1-44. [3]Poddubnyy D, van Tubergen A, Landewe R, Sieper J, van der Heijde D. Development of an ASAS-endorsed recommendation for the early referral of patients with a suspicion of axial spondyloarthritis. Annals of the rheumatic diseases. 2015;74(8):1483-7. [4]Rudwaleit M, van der Heijde D, Landewe R, Akkoc N, Brandt J, Chou CT, et al. The Assessment of SpondyloArthritis International Society classification criteria for peripheral spondyloarthritis and for spondyloarthritis in general. Annals of the rheumatic diseases. 2011;70(1):25-31. Acknowledgements: This work was supported by a Health Services Research Grant (HSRG) from the Singapore Ministry of Health National Medical Research Council [grant number: NMRC/HSRG/0075/2017]. Disclosure of Interests: None declared