FRI0341 RISK FACTORS FOR AXIAL INVOLVEMENT IN EARLY PSORIATIC ARTHRITIS

Abstract

Background:Axial Involvement in psoriatic arthritis (PsA) is quite common [1]. Predictors of axial involvement at early-stage of disease haven’t been sufficiently studied.Objectives:To identify predictors of axial involvement in PsA patients (pts) at early-stage of disease.Methods:95 patients (pts) (M/F–47/48) with early PsA fulfilling the CASPAR criteria were included. All pts had peripheral arthritis for≤2 years; no inflammatory back pain (IBP) pts were specifically selected. Mean (Me) age 36.5±10.7 yrs, disease duration 12.2±10.3 mo. Pts underwent standard clinical examination of PsA activity. Me disease activity indexes DAS=4.0±1.4, DAS28=4.2±1.1, BASDAI=4.5±1.6; Me pts global disease activity VAS 56.9±17.1. All patients were evaluated for the presence of IBP by ASAS criteria, underwent sacroiliac joints (SIJs) X-ray (pelvic radiographs) and HLA B27 antigen status study. MRI of SIJs was performed in 79 pts, regardless of IBP presence, on Signa Ovation 0.35T. Radiographic sacroiliitis (R-SI) was identified according to New York criteria (unilateral grade≥3 or bilateral grade≥2). Bone marrow edema/ osteitis on MRI (STIR) was considered active MRI sacroiliitis (MRI-SI). X-ray and MRI results were evaluated by an independent reader. IBP was observed in 63 (66.3%) cases, MRI-SI in 28 of 79 (35.4%) examined cases, R-SI in 29 (30.5%) cases. Skin lesion severity was evaluated as body surface area (BSA) affected: minor at <3%, mild at 3-10%, severe at >10%. Pts were split into 2 groups (gr.): those with axial involvement (axPsA), that is with IBP and/or R-SI and/or MRI-SI; and those without axial involvement (having only peripheral PsA [pPsA]).The axPsA gr. included 65 (68.4%) cases, the pPsA gr. 30 (31.6%) cases. Multi-dimensional step-by-step discriminant analysis was used to identify a group of features that are more typical for the axPsA patients.Results:The following features proved to be the most informative: male sex (р = 0.300), presence of HLA B27 (р = 0.107), mild or high DAS (р = 0.098), skin lesion severity BSA>3% (р = 0.118), and CRP > 5 mg/L (0.038).Sensitivity of model 79.0%, specificity of model 57.7%. Area under ROC curve 0.756; 95% CI (0.642-0.869).Conclusion:It is a combination of features – male sex, HLA-B27 positivity, mild or high activity of peripheral arthritis according to DAS, CRP > 5 mg/L, and BSA> 3% – that constitutes a clinical predictor for the development of axial involvement in early psoriatic arthritis.