POS0498 ASSOCIATIONS BETWEEN EXTRA-MUSCULOSKELETAL MANIFESTATIONS AND RADIOGRAPHIC PROGRESSION IN AXIAL SPONDYLOARTHRITIS
Authors: S. S. Zhao, N. Harvey, L. A. Bradbury, L. S. Gensler, Z. LI, M. Rahbar, M. M. Ward, M. H. Weisman, J. D. Reveille, T. H. Kim, M. Brown
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Extra-musculoskeletal manifestations (EMMs) are common and important features of axial spondyloarthritis (axSpA) that are associated with disease activity, but whether EMMs are associated with radiographic progression is unclear. <h3>Objectives:</h3> To examine the association between uveitis, psoriasis, inflammatory bowel disease (IBD) and radiographic progression in radiographic-axSpA <h3>Methods:</h3> We used clinical and radiographic data from the Australo-Anglo-American Spondyloarthritis Consortium (TASC). Radiographs were scored using a modified version of mSASSS (original mSASSS scores of ≥1 minus 1) to reduce ambiguity between scores of 0 and 1 [1]. For the C-spine, missing vertebra scores were replaced with the mean if &lt;4 were missing; the same was applied to L-spine. Total mSASSS was invalidated if ≥4 scores were missing in either C- or L-spine. Baseline was defined as date of the first radiograph. Separate analyses were performed for each self-reported baseline EMM. We used generalized estimating equations with mSASSS as outcome, and each EMM, time (years) and EMM-time-interaction as independent variables, to assess whether change in mSASSS over time differed between groups. Primary analyses used complete cases adjusting for baseline covariates: mSASSS, gender, symptom duration, CRP, TNFi use (yes, no, missing), and smoking (never, previous, current). HLA-B27 was not included as a covariate because it was not associated with progression. Models were repeated using ASDAS instead of CRP and using multiple imputation for missing covariates and a missing-indicator for missing EMMs. Where possible, we replicated analyses using an independent Korean dataset with unmodified mSASSS. <h3>Results:</h3> Analyses of TASC included 1,150 individuals (mean age 44 (14) years, 75% male, 84% HLA-B27 positive) over 3,441 patient-years (median follow-up 2.0 years, median 2 (IQR 1, 3) radiographs). 668, 666, 668 participants completed questionnaires for uveitis (prevalence 32%), psoriasis (11%) and IBD (7%), respectively. Those with uveitis were older (45 vs 41 years), more frequently HLA-B27 positive (90 vs 78%), more often ever-smokers (63 vs 55%), but had similar baseline mSASSS (mean 9 vs 10 units) and CRP (mean 1.0 vs 0.9 mg/dL) (Table 1). The group with psoriasis were older (46 vs 42 years), less often HLA-B27 positive (70 vs 83%), but otherwise comparable to those without psoriasis. Those with IBD were older (49 vs 42 years) and more often ever-smokers (76 vs 56%). In complete case analyses, increase in mSASSS over time was statistically greater in the presence of uveitis (equivalent of 1.9 units difference in mSASSS over 10 years on average; 95%CI 1.2, 2.5; p&lt;0.001), psoriasis (2.2 units/10 years; 95%CI 1.3, 3.1; p&lt;0.001), but not IBD (-0.8 units/10 years; 95%CI -1.9, 0.3; p=0.168). Results were similar when using ASDAS instead of CRP, or when using multiple imputation and missing-indicator for missing EMMs. Only uveitis was included in the Korean replication dataset of 768 individuals (mean age 32 years, 90% male, 97% HLA-B27 positive, 6,974 patient-years). Presence of uveitis (prevalence 37%) was also associated with greater radiographic progression (4.5 units/10 years; 95%CI 3.0, 6.0; p&lt;0.001). <h3>Conclusion:</h3> Uveitis and, to a lesser extent, psoriasis were associated with greater radiographic progression, independent of other key predictors. Groups with these EMMs may benefit from targeted management. Further research is needed to examine any associations between EMM severity and radiographic progression. <h3>REFERENCES:</h3> [1] Cortes A. <i>Ann Rheum Dis</i> 2015;74:1387–93 <b>Table 1.</b> Baseline characteristics of individuals with axial spondyloarthritis with and without each extra-musculoskeletal manifestation. <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> Sizheng Steven Zhao UCB, Novartis, Abbvie, UCB, Nicholas Harvey: None declared, Linda A Bradbury: None declared, Lianne S Gensler Acelyrin, Janssen, Novartis, Pfizer, UCB, Novartis, UCB, Zhixiu Li: None declared, Mohammad Rahbar: None declared, Michael M Ward: None declared, Michael H Weisman: None declared, John D Reveille: None declared, Tae-Hwan Kim: None declared, Matthew Brown Novartis, UCB, Clementia, Incyte, Ipsen, UCB, Xinthera, UCB.