Background: Psoriasis, uveitis and inflammatory bowel disease (IBD) are extra-articular manifestations (EAMs) that can occur in both axial Spondyloarthritis (axSpA) and psoriatic arthritis (PsA). Their prevalence has been outlined independently in a recent meta-analysis¹ for axSpA and in several series in PsA with variable results. Although the diagnostic delay of inflammatory arthritis has been reduced in the last years, it remains a significant unmet need, particularly in axSpA. There are limited data on the relationship between diagnostic delay and the appearance of EAMs.

Objectives: To explore the prevalence of EAMs in a cohort of axSpA and PsA patients, and its relationship to disease duration and possible diagnostic delay in both groups.

Methods: Cross-sectional, single centre, observational cohort study of consecutive patients attending a large tertiary specialist clinic. All subjects provided written consent (2005-2018). Only patients fulfilling the modified New York (mNY) criteria for ankylosing spondylitis and CASPAR criteria for PsA were considered for this analysis. Demographic and clinical data were retrieved during enrolment and cross-referenced with the clinical notes. To explore the relationship between presence of EAMs, disease duration and delay to diagnosis, only uveitis and IBD were considered because of psoriasis being common in the PsA group. Univariate (Mann Whitney U-test) and multivariate analysis (binary logistic regression) with variables of sex, age, disease duration and diagnostic delay were performed.

Results: Data from 988 patients were available for analysis (n= 418 axSpA, n=570 PsA). Demographic and clinical characteristics are summarised in Table 1.

In the axSpA group, 187 cases (44.7%) presented with EAMs (including psoriasis) and 67 (16.02%) of these had more than 1 EAM. In the PsA group, 32 cases (5.6%) presented with EAM (excluding psoriasis) and only 3 cases (0.5%) had more than one EAM.

In the PsA group, a median delay of 4 years (IQR 2-9) was observed between psoriasis onset and PsA. In 42 cases the psoriasis appeared after the PsA onset. The predominant PsA phenotype was polyarticular (n=298; 52.3%) of which n=118, 20.7% had erosive disease. 101 (17.7%) had a predominantly axial phenotype.

Disease duration and delay to diagnosis were longer in the axSpA group (p<0.0001). Further univariate analysis showed an association between disease duration and the presence of EAMs when analysing the whole cohort (p<0.001) and the axSpA group (p<0.001), but not in the PsA group (p=0.832). The diagnostic delay was associated to the presence of EAMs in the whole cohort (p<0.001), but not in the individual disease groups. In the multivariate analysis only disease duration was related to presence of EAMs in the whole cohort (OR 1.064 95%IC 1.044-1.086) and axSpA group (OR 1.043 95%IC 1.016-1.070).

Conclusion: The prevalence of EAMs (uveitis and IBD) in this cohort appears higher in axSpA than PsA and is related to disease duration. Diagnostic delay occurs in both groups being more significant in axSpA, and should be highlighted as a priority research area in order to improve the outcome of people affected by SpA.

References: [1] De Winter JJ, et al. Arthritis Res Ther (2016); 18:196.

Disclosure of Interests: Xabier Michelena-Vegas: None declared, Sayam Dubash: None declared, Ann Morgan: None declared, Helena Marzo-Ortega Grant/research support from: Janssen, Novartis and Pfizer, Consultant for: AbbVie, Celgene, Janssen, Eli-Lilly, Novartis and UCB, Speakers bureau: AbbVie, Celgene, Janssen, Eli-Lilly, Novartis and UCB