POS0501 GENDER AND AGE-OF-ONSET ARE ASSOCIATED WITH 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> Gender and age-of-onset are associated with radiographic damage in axial spondyloarthritis (axSpA), but detailed analyses of both factors are lacking. <h3>Objectives:</h3> First, to examine the associations between gender and (1) longitudinal radiographic progression, including specifically at the cervical and lumbar spine, (2) baseline radiographic damage at sacroiliac joints (SIJs) and hips. Second, to examine the same associations with age-of-onset as the explanatory variable. <h3>Methods:</h3> We used clinical and radiographic data from the Australo-Anglo-American Spondyloarthritis Consortium (TASC). Age-of-onset dichotomized into juvenile or adult (&lt;16/≥16 years) onset. Spine 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]. Baseline was defined as date of the first radiograph. For SIJs and hips, baseline radiographs were also scored using BASRI on a scale of 0-4 (for normal, suspicious, mild, moderate, severe) taking a mean of both sides. For longitudinal mSASSS progression, we used generalized estimating equations (GEE) with mSASSS as outcome, and gender, time (years) and gender-time-interaction as independent variables, to assess whether change in mSASSS over time differed between groups. GEE was repeated for the age-onset analysis. Models were adjusted for baseline covariates: mSASSS, gender (except in gender analyses), symptom duration, CRP, TNFi use (yes, no, missing), number of extra-musculoskeletal manifestations (EMMs: uveitis, psoriasis, IBD), number of comorbidities, and sm For cross-sectional analysis of BASRI, we used linear regression models including gender, juvenile-onset, and the above covariates. Additionally, multiple imputation was used for missing covariates for all models. oking status (never, previous, current). <h3>Results:</h3> Analyses included 1,150 individuals (mean age 44 (14) years, 84% HLA-B27 positive) over 3,441 patient-years (median follow-up 2.0 years, median 2 (IQR 1, 3) radiographs). Among 81% with available baseline data, 38% were on a TNFi. 857 (75%) were male and, compared to females, had longer mean symptom duration (20 vs 18 years, p=0.01), higher baseline mSASSS (13 vs 4 units, p&lt;0.001), were more often HLA-B27 positive (85 vs 80%, p=0.04) and ever smokers (63 vs 53%, p=0.03), and less often had uveitis (18 vs 23%, p=0.048). 154 (13%) were juvenile-onset and had expectedly longer symptoms duration, but similar proportions for HLA-B27, smoking status and EMMs. TNFi use, CRP and ASDAS were comparable across both gender and onset (all p&gt;0.10). In longitudinal models of radiographic progression, male gender was associated with greater total mSASSS progression over time (3.4 mSASSS units over 10 years on average; 95%CI 2.6, 4.2; p&lt;0.001). No difference in rate of progression at the C-spine was noted between gender (-0.3 units/10 years; 95%CI -0.6, 0.1; p=0.16), whereas males had more rapid progression at the L-spine (3.1 units/10 years; 95%CI 2.6, 3.7; p&lt;0.001). Total mSASSS progression was similar between juvenile/adult-onset (Figure 1); statistical difference for C-spine progression is unlikely to be clinically meaningful (0.9 units/10 years; 95%CI 0.5, 1.5; p&lt;0.001). In cross-sectional models of radiographic damage, males had higher BASRI score at SIJs and hips than females (Figure 2). Juvenile onset was associated with higher hip BASRI score, compared with adult-onset. All results were similar when using multiple imputation for missing covariates. <h3>Conclusion:</h3> Males with axSpA have more severe hip disease, and greater mSASSS radiographic progression, driven by more rapid progression at the L-spine than is observed in females. Participants with juvenile-onset axSpA had greater hip radiographic damage. <h3>REFERENCES:</h3> [1] Cortes A. <i>Ann Rheum Dis</i> 2015;74:1387–93 <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.