E148 Exploring predictors of functional outcome in axial spondyloarthritis: insights from the Ankylosing Spondylitis Registry of Ireland (ASRI)

Abstract Background/Aims Axial spondyloarthritis (axSpA) is a chronic inflammatory condition affecting the axial skeleton, often associated with functional limitations. The Bath Ankylosing Spondylitis Functional Index (BASFI) is a validated score used to evaluate functional limitations in axSpA; however, predictors of worse BASFI scores remain incompletely understood. This study aims to identify demographic and clinical factors associated with worse BASFI in axSpA, with emphasis on gender differences. Methods This study was performed within the framework of ASRI (Ankylosing Spondylitis Registry of Ireland), a multicentre observational cohort of axSpA patients. A standardised clinical assessment is performed on each patient. Structured interviews provide patient-reported data, including BASFI and BASDAI, measured on 0-10 scale, with higher numbers indicative of severity. BASMI assesses structural severity (0-10). Inferential statistical analyses were performed to explore associations between clinical and sociodemographic factors and BASFI. SPSS was used for statistical analyses. Results 917 participants were enrolled in ASRI (see Table 1 for demographics and clinical characteristics). Mean BASFI was 3.6, indicating mild-moderate functional limitation. BMI correlated significantly with BASFI (r = 0.23, p 0.001); each 1-unit BMI increase corresponded to 0.1 BASFI increase (p 0.001), with no gender difference. Gender, disease duration (r = 0.02, p = 0.59), diagnostic delay (r= -0.002, p = 0.95), and extra-musculoskeletal manifestations (EMM; uveitis, psoriasis, IBD) were not significantly associated with BASFI. BASFI correlated significantly (p 0.05) with BASMI and BASDAI elements, including tragus-to-wall distance (r = 0.29), lumbar side flexion (r= -0.36), Schober’s test (r= -0.33), cervical rotation (r= -0.46), morning stiffness duration (r = 0.51) and severity (r = 0.65), neck, back and hip pain level (r = 0.59), other pain level (r = 0.51), discomfort to touch (r = 0.52), and tiredness (r = 0.62). In women, reduced intermalleolar distance, indicating hip involvement, correlated strongly with worse BASFI (r= -0.34, p = 0.002); no such correlation was observed in men. Conclusion BMI and hip involvement, particularly in women, contribute significantly to functional impairment in axSpA. Functional outcomes were not influenced by disease duration, diagnostic delay, or EMMs. Correlations between BASFI and multiple BASDAI/BASMI components highlight the multifactorial nature of functional limitation. Further research is needed to examine the role of weight management and targeted hip disease management, especially in women, in improving axSpA. Disclosure M. Eltahir: None. C. Macgearailt: None. F. O’ Shea: None. G. Fitzgerald: None.