AB0674 CLINICAL AND IMAGING FEATURES IN SPONDYLOARTHRITIS PATIENTS WITH AND WITHOUT HLA-B27 AND HLA-B51 RED CELL DISTRIBUTION WIDTH AND FATIGUE IN AXIAL SPONDYLOARTHRITIS: A SLEEPER SIGNAL

Background: Axial spondyloarthritis (axSpA) is a chronic inflammatory disease predominantly involving the axial skeleton and sacroiliac joints. Although the exact aetiology remains largely unknown, there is thought to be an immune- driven element. Vitamin D deficiency has been associated with a number of autoimmune diseases and is thought to play an important role in modulating the immune system. Low vitamin D levels may contribute to the development and progression of axSpA 1 . Objectives: To study the possible associations between low vitamin D and disease activity in axSpA. Methods: A systematic literature search using Medline, Embase and Cochrane was performed using MESH search terms “ankylosing spondyli- tis”, “axial spondyloarthropathy” and “vitamin D”. Articles examining disease activity measured by BASDAI, ASDAS-CRP, ESR and CRP identified through title/abstract screening, were included in the study, with relevant information extracted. Results: Out of 495 articles identified from the initial search, 19 observa- tional studies which were mostly (89%) cross-sectional studies were identified. There was considerable heterogeneity between studies, including in the definition of vitamin D deficiency, latitude where study took place and seasonal variation. Vitamin D levels were often lower in patients with axSpA compared to controls. Seventeen studies found no association with vitamin D deficiency and disease activity. The exceptions included one study which measured serum vitamin D receptor levels as opposed to serum 25 (OH) D or 1,25 (OH)2 D concentrations, and another study whose recruitment occurred over four years and therefore seasonal variation may conflict results. Patients taking NSAIDs or anti-TNF had no difference in vitamin D levels. Conclusion: Vitamin D deficiency is more prevalent in axSpA but does not seem to associate with increased disease activity. Longitudinal studies are required to better define these links. Background: Despite being commonly expressed in the general population, the human leucocyte antigen (HLA)-B27 allele strongly increases the susceptibility to develop spondyloarthritis (SpA). Likewise, the association between the HLA- B51 allele and the development of Behçet’s disease is well documented. How-ever, the exact mechanisms responsible for their pathologic role are still a matter of debate. Moreover, anecdotal reports show an association between HLA-B51 and the clinical spectrum of SpA. Objectives: To investigate the clinical and imaging findings of SpA patients according to the absence or presence of HLA-B27 or HLA-B51. Methods: We retrospectively analyzed 236 patients with axial or peripheral SpA, according to the ASAS criteria, referring to two tertiary Rheumatology Clinics between 2017 and 2019. All patients had been tested for HLA-B alleles. Patients with HLA-B51 haplotype and fulfilling the criteria for Behçet’s disease were excluded. Results: Background: Fatigue is a ubiquitous feature of autoimmune conditions, and axial Spondyloarthritis (axSpA) is no exception, with over 50% of patients report-ing some degree of fatigue 1 . Erythrocyte size variability (as measured by red cell distribution width (RDW)) has been found to correlate with fatigue in a cohort of systemic lupus erythematous (SLE) patients and may reflect early iron defi- ciency 2 . We investigate whether this finding holds true in axSpA. Objectives: To investigate the relationships between fatigue, disease activity, and RDW (as a proxy for functional iron deficiency) in patients with axSpA. Background: Occasional findings of anti-citrullinated-protein-antibodies (ACPA) and anti-nuclear-antibodies (ANA) were rarely described in literature on Psoriatic Arthritis (PsA) and on Spondyloarthritis (SpA) in general. How these autoimmune dysregulations can affect the course of them is not yet understood. Objectives: The aim of our study is to evaluate if the presence of ACPA and ANA can determine different disease subsets and influence the DMARDs monotherapy (methotrexate) drug survival (DSM) and b-DMARDs multi-failure patients (MF). Methods: We conducted a retrospective study on patients with Psoriatic Arthri- tis (PsA) and Spondyloarthritis that fulfilled the ASAS and CASPAR criteria. Patients with diagnosis DMARDs (start-time), b-DMARDs (oligoarticular (OA), polyarticular (PA), enthesitis (EA), axial involvement (AI)), comorbidities (NC), Comorbidity (CCI). patients PsA SpA) ACPA start-time, PsA