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Axial Disease in Psoriatic Arthritis study: defining the clinical and radiographic phenotype of psoriatic spondyloarthritis
  1. Deepak R Jadon1,2,
  2. Raj Sengupta1,
  3. Alison Nightingale3,
  4. Mark Lindsay3,
  5. Eleanor Korendowych1,
  6. Graham Robinson1,
  7. Amelia Jobling4,
  8. Gavin Shaddick4,
  9. Jing Bi5,
  10. Robert Winchester5,
  11. Jon T Giles5,
  12. Neil J McHugh1,3
  1. 1Department of Rheumatology, Royal National Hospital for Rheumatic Diseases, Bath, UK
  2. 2Department of Rheumatology, Addenbrooke's Hospital, Cambridge, UK
  3. 3Department of Pharmacy & Pharmacology, University of Bath, Bath, UK
  4. 4Department of Mathematical Sciences, University of Bath, Bath, UK
  5. 5Columbia College of Physicians & Surgeons, New York, New York, USA
  1. Correspondence to Dr Deepak Jadon, Rheumatology Department, Royal National Hospital for Rheumatic Disease, Upper Borough Walls, Bath BA1 1RL, UK; jadondr{at}


Objectives To compare the prevalence, clinical and radiographic characteristics of psoriatic spondyloarthritis (PsSpA) in psoriatic arthritis (PsA), with ankylosing spondylitis (AS).

Methods A 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.

Results The 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).

Conclusions In 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.

  • Psoriatic Arthritis
  • Ankylosing Spondylitis
  • Spondyloarthritis
  • Outcomes research

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  • Handling editor Tore K Kvien

  • Contributors All contributors to this manuscript and study have been acknowledged as coauthors or in the ‘acknowledgement’ section of the manuscript.

  • Funding This study was funded through an unrestricted Investigator-Initiated Research grant by Pfizer Limited.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Ethics approval Frenchay Regional Ethics Committee, Bristol, UK.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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