Axial Disease in Psoriatic Arthritis study: defining the clinical and radiographic phenotype of psoriatic spondyloarthritis

Abstract

ObjectivesTo compare the prevalence, clinical and radiographic characteristics of psoriatic spondyloarthritis (PsSpA) in psoriatic arthritis (PsA), with ankylosing spondylitis (AS).MethodsA prospective single-centre cross-sectional observational study recruited consecutive PsA and AS cases. Participants completed outcome measures, and underwent clinical examination, axial radiographic scoring and HLA-sequencing. Multivariable analyses are presented.ResultsThe 402 enrolled cases (201 PsA, 201 AS; fulfilling classification criteria for respective conditions) were reclassified based upon radiographic axial disease and psoriasis, as: 118 PsSpA, 127 peripheral-only PsA (pPsA), and 157 AS without psoriasis (AS) cases. A significant proportion of patients with radiographic axial disease had PsSpA (118/275; 42.91%), and often had symptomatically silent axial disease (30/118; 25.42%). Modified New York criteria for AS were fulfilled by 48/201 (23.88%) PsA cases, and Classification of Psoriatic Arthritis criteria by 49/201 (24.38%) AS cases. pPsA compared with PsSpA cases had a lower frequency of HLA-B*27 (OR 0.12; 95% CI 0.05 to 0.25). Disease activity, metrology and disability were comparable in PsSpA and AS. A significant proportion of PsSpA cases had spondylitis without sacroiliitis (39/118; 33.05%); they less frequently carried HLA-B*27 (OR 0.11; 95% CI 0.04 to 0.33). Sacroiliac joint complete ankylosis (adjusted OR, ORadj 2.96; 95% CI 1.42 to 6.15) and bridging syndesmophytes (ORadj 2.78; 95% CI 1.49 to 5.18) were more likely in AS than PsSpA. Radiographic axial disease was more severe in AS than PsSpA (Psoriatic Arthritis Spondylitis Radiology Index Score: adjusted incidence risk ratio 1.13; 95% CI 1.09 to 1.19).ConclusionsIn a combined cohort of patients with either PsA or AS from a single centre, 24% fulfilled classification criteria for both conditions. The pattern of axial disease was influenced significantly by the presence of skin psoriasis and HLA-B*27.

Back pain in psoriatic arthritis: defining prevalence, characteristics and performance of inflammatory back pain criteria in psoriatic arthritis

“…Sacroiliitis is more commonly bilateral in AS but may be either unilateral or bilateral in AxPsA 21. However, Jadon et al did not find unilateral or asymmetrical grade sacroiliitis to be characteristic of AxPsA 16. As well, syndesmophytes progress caudal to cranial in AS compared with syndesmophytes in AxPsA which progress randomly 22.…”

“…Axial involvement in PsA is a marker of severity and those with axial disease often have worse outcomes compared with peripheral arthritis alone 1. Although radiographic severity appears to be worse in AS than in AxPsA as measured by the Bath AS Radiology Index14 and number of syndesmophytes,15 measures of disease activity, disability and metrology were high in both AxPsA and AS, with no statistically significant difference between groups 16. As well, the response to treatment may be different; axial and peripheral articular manifestations of spondyloarthritis respond differently to treatment with sulfasalazine 17…”

Association of Inflammatory Bowel Disease and Acute Anterior Uveitis, but Not Psoriasis, With Disease Duration in Patients With Axial Spondyloarthritis

“…In addition to the genetic component, imaging features in patients with axial SpA with or without psoriasis (or psoriasis patients with spondylitis) seem to present differently, with sacroiliitis being preferentially located unilaterally, aberrant expression of syndesmophytes, and more frequent involvement of the cervical spine (28)(29)(30)(31)(32). Consistent with the results of the present study, psoriasis was associated with less inflammation, as evidenced on MRI of the spine and sacroiliac joints, and with less radiographic damage in a follow-up study of patients with early disease (10).…”

IL-17 in the immunopathogenesis of spondyloarthritis

“…To date, the HLA-B27 region represents the strongest genetic risk association identified in axSpA, PsA and reactive arthritis [31][32][33] , and positivity for HLA-B27 is strongly associated with sacroiliitis in both AS and PsA. In addition, multiple other variants within the MHC class I loci are associated with PsA (including HLA-B39, HLA-Cw6, HLA-B38 and HLA-B08) or AS (HLA-A02, HLA-B07), with some associations most evident when patients are stratified by clinical characteristics 30,[34][35][36] . The association of SpA with a variety of different HLA-B loci indicates that several immunological mechanisms could be altered by these genetic associations, including T cell repertoire selection and antigen presentation 37 .…”