OP0026 CLINICAL AND IMAGING-BASED CHARACTERIZATION OF A PROSPECTIVE COHORT OF PATIENTS WITH AXIAL PSORIATIC ARTHRITIS (AXIAL PsA). GESPIC-AXIAL PsA: RESULTS OF AN INTERIM ANALYSIS

Abstract

BackgroundPsoriatic arthritis (PsA) is a chronic inflammatory disease, which is subsumed together with axial spondyloarthritis (axial SpA) under the umbrella term spondyloarthritis, whose clinical presentations are very heterogeneous. Axial involvement (axial PsA) has been described to be present in 34% of PsA patients [1] and has been systematically investigated only retrospectively or in cross-sectional studies [2]. Although axial PsA seems to have similar characteristics to axial SpA, it is not clear whether axial PsA and axial SpA, are a spectrum of the same disease with different expression patterns or different diseases with great similarities.ObjectivesTo prospectively investigate the clinical and imaging morphology patterns in a well-defined cohort of patients with axial PsA from the German SPondyloarthritis Inception Cohort (GESPIC).MethodsProspective, longitudinal, observational study of patients with an imaging confirmed diagnosis of axial PsA. In addition to clinical and laboratory characterization, conventional radiographs and magnetic resonance imaging (MRI) - scans of the entire spine and sacroiliac joints (SIJs) are performed at the baseline visit and patients are followed up every 6 months according to a predefined protocol. After 2 years, additional imaging (X-ray and MRI) is performed for follow-up. In this interim analysis baseline data are presented.ResultsBetween August 2019 and December 2021, 85 axial PsA patients were included. The mean age was 45.2 ± 12.9 years with a proportion of 55.3% female patients. Peripheral involvement was present in 43 (50.6%) patients, HLA-B27 was positive in 39 (45.9%), and C-reactive protein was elevated (>5mg/l) in 27 (31.8%) patients. Inflammatory back pain (IBP) in the discretion of the treating rheumatologist was present in 64 (75.3%) patients (Table 1). The modified New York criteria were fulfilled in 44.9% (n=35). MRI of the SIJ showed active inflammatory changes in 44 (55%) and structural changes in 59 (73.8%) patients. MRI of the spine showed active inflammation in 60% (n=48). Exclusively active and/or structural changes of the spine without changes in the SIJ were seen in 18.8% (n=15) (Figure 1).Table 1.Characteristics of patients with axial PsAParametersAxial PsA (n=85)Age in years (mean ± SD)45.2 ± 12.9Female sex, n (%)47 (55.3%)Inflammatory back pain (IBP) present, n (%)64 (75.3%)Peripheral Involvement, n (%)43 (50.6%)Nail Involvement, n (%)39 (45.9%)PASI-Score (mean ± SD)3.3 ± 5.1BASDAI (mean ± SD), 0-104.9 ± 2.0BASFI (mean ± SD), 0-103.8 ± 2.5ASDAS-CRP (mean ± SD)2.8 ± 1.0DAPSA (mean ± SD)14.5 ± 9.2HLA-B 27 positive, n (%)39 (45.9%)CRP >5mg/l, n (%)27 (31.8%)ASDAS-CRP =Ankylosing Spondylitis Disease Activity Score - CRP, BASDAI = Bath Ankylosing Spondylitis Disease Activity Index, BASFI =Bath Ankylosing Spondylitis Functional Index, CRP = C-reactive protein, DAPSA = Disease Activity in PSoriatic Arthritis-Score, PASI = Psoriasis Area Severity Index, PsA = Psoriatic arthritis, SD = standard deviation.Figure 1.MRI-imaging patterns of axial PsA patients (n=80*). MRI= magnetic resonance imaging, SIJs= sacroiliac joints. *Full imaging data available for 80 patients only due to variable reasons.ConclusionIn the here presented interims analysis of the baseline data of our prospective cohort study of patients with an imaging-based diagnosis of axial PsA, it is shown that these patients are less frequently HLA-B27 positive and more frequently female when compared to previously described cohorts of “classical” axial SpA patients. Noteworthy, nearly 20% of the patients showed an isolated spinal involvement without active or structural changes in the SIJs.