Background/Purpose: Although spinal involvement has been well studied in ankylosing spondylitis,¹ very few studies in psoriatic arthritis (PsA) have characterized patients with axial involvement. The objective of this analysis was to understand the prevalence and describe the baseline characteristics of PsA patients with and without axial involvement in the US-based Corrona Psoriatic Arthritis/Spondyloarthritis (PsA/SpA) registry.

Methods: This cross-sectional descriptive study included all patients with PsA enrolled in the Corrona PsA/SpA registry between March 2013 and March 2016 with non-missing data on axial involvement, defined as having a physician-reported presence of spinal involvement at enrollment, or an MRI or x-ray showing sacroiliitis. Descriptive analyses of patient demographics, clinical measures, patient-reported outcomes and treatment characteristics were reported at the time of enrollment for patients with vs without axial involvement. Statistical comparisons between subgroups were evaluated using P values from t-tests for continuous variables and chi-squared tests for categorical variables.

Results: As of March 2016, there were a total of 1530 patients with PsA in the Corrona PsA/SpA registry who had non-missing data on physician-reported axial involvement, including 192 patients (12.5%) with axial involvement and 1338 patients (87.5%) without axial involvement. Both subgroups were similar with regards to sex, race, body mass index, disease duration, overall presence of dactylitis and prevalence of most comorbidities (e.g., cardiovascular disease, any cancer, diabetes and serious infection). However, patients with axial involvement were younger (50.4 vs 54.4 years) and significantly more likely to have enthesitis (20.7% vs 19.2%), a history of depression (22.9% vs 12.6%) and biologic use (66.1% vs 54.3%) at enrollment compared to patients without axial involvement. Patients with axial involvement were also more likely to have moderate/severe psoriasis (body surface area > 3%) at enrollment compared with patients without axial involvement, and had worse disease as measured by nail psoriasis, enthesitis counts, achievement of minimal disease activity, AS disease activity and functional index scores, C-reactive protein levels and patient-reported outcomes (Table).

Conclusion: Data from the Corrona PsA/SpA registry showed that patients with PsA and axial involvement were more likely to have moderate/severe psoriasis with significantly higher disease activity at the time of registry enrollment compared to those without axial involvement. These findings demonstrate the overall impact of axial involvement on disease activity and highlight the importance of monitoring patients with PsA for signs of axial symptoms or spinal involvement on imaging.

References:

1.    Braun A, et al. Ann Rheum Dis. 2011;70(10):1782-7.