AXIAL PSORIATIC ARTHRITIS VERSUS AXIAL SPONDYLOARTHRITIS WITH PSORIASIS IN CLINICAL PRACTICE

Background: Spondyloarthritis (SpA) comprise a complex group of inflammatory arthropathies that can involve both axial and peripheral joints, often associated with extra-musculoskeletal manifestations, particularly psoriasis. The distinction between Psoriatic Arthritis (PsA) with axial involvement and axial SpA (axSpA) with concomitant psoriasis has been a topic of debate, potentially influencing clinical decisions. Objectives: To identify clinical and demographic characteristics associated with clinician’s decision to diagnose patients with psoriasis and axial disease as axSpA or as PsA with axial involvement in practical clinical settings. Methods: All adult patients registered in the Rheumatic Portuguese Disease Register (Reuma.pt) with the clinical diagnosis of PsA with axial involvement (axPsA) or axSpA with concomitant psoriasis were included. Bivariate and multivariate analysis were performed to identify clinical and demographic characteristics associated with the clinical diagnosis of axPsA or axSpA. Results: Out of 854 patients, 88.3% (n=754) received a diagnosis of axPsA and 11.7% (n=100) were diagnosed with axSpA with psoriasis. The diagnosis of axPsA included concomitant peripheral involvement in 82.2% of patients (n=620) and exclusive axial involvement in 17.8% (n=134). In axSpA diagnosis, the prevalence of concomitant peripheral involvement was 48% (n=48). Considering the whole cohort, axSpA diagnosis was associated with less peripheral involvement (OR 0.20, 95% CI 0.13-0.31; p<0.001), younger age at diagnosis (axSpA 36.7 ± 9.4 vs axPsA 43.8 ± 13.1; p<0.001) and at symptom onset (axSpA 30.1 ± 9.7 vs axPsA 39.6 ± 12.9; p<0.001) and higher positivity for HLA-B27 (OR 8.95; 95% CI 5.24-15.28; p<0.001) (Table 1). Regarding extra-articular manifestations, uveitis (OR 7.59; 95% CI 4.5-12.81; p<0.001) and inflammatory bowel disease (OR 21.02; 95% CI 8.01-55.18; p<0.001) were associated positively, while dactylitis was associated negatively with axSpA diagnosis (OR 0.13; 95% CI 0.06-0.29; p<0.001). axSpA patients more commonly received bDMARDs (OR 3.82; 2.13-6.84; p<0.001) and had a longer time from symptom onset until start of first bDMARD (axSpA 13.7 ± 9.3 vs axPsA 9.5 ± 9.1; p<0.001). Cardiovascular comorbidities were negatively associated with axSpA (OR 0.53; 95% CI 0.32 - 0.88; p<0.013). Multivariate analysis identified HLA-B27 positivity, younger age at symptom onset, presence of uveitis and inflammatory bowel disease and lower prevalence of dactylitis as independently associated with axSpA diagnosis. When considering patients with exclusive axial involvement (N=186), axSpA diagnosis was associated with a younger age at diagnosis (axSpA 36.4 ± 10.3; vs axPsA 43.9 ± 13.8; p<0.001) and at symptom onset (axSpA 29.3± 10.1 vs axPsA 38.3 ± 13.6; p<0.001), a higher prevalence of HLA-B27 (OR 8.55; 95% CI 3.59-20.4; p<0.001) and uveitis (OR 7.7; 95% CI 3.0-19.2; p<0.001) (Table 2). Regarding treatment, axSpA patients were more frequently treated with bDMARDs (OR 4.59; 95% CI 2.13 - 9.90; p<0.001) and had a longer time from symptom onset until start of first bDMARD (axSpA 14.8 ± 10.2 vs axPsA 8.5 ± 7.9; p<0.001). However, multivariate analysis did not identify any variables independently associated with the diagnosis of axPsA or axSpA. Conclusion: Patients with axPsA diagnosis exhibit more frequently concomitant peripheral involvement, whereas those with axSpA diagnosis have more often exclusive axial involvement, are younger and more frequently HLA-B27 positive. However, when considering patients with exclusive axial involvement, no differences could be identified between axSpA with psoriasis and axPsA diagnosis. In clinical practice, clinicians tend to diagnose patients with psoriasis as axSpA when axial involvement predominates and there are no peripheral manifestations. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests: None declared. DOI: 10.1136/annrheumdis-2024-eular.3485 Keywords: Enthesitis, Uveitis, Observational studies/registry, Real-world evidence Citation: , volume 83, supplement 1, year 2024, page 926Session: Spondyloarthritis (Poster View)

Enthesitis, Uveitis, Observational studies/registry, Real-world evidence