title: Axial Disease in Psoriatic Arthritis study: defining the clinical and radiographic phenotype of psoriatic spondyloarthritis.
abstract: OBJECTIVE
  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 andHLA-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 ofHLA-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 carriedHLA-B*27(OR 0.11; 95% CI 0.04 to 0.33). Sacroiliac joint complete ankylosis (adjusted OR, ORadj2.96; 95% CI 1.42 to 6.15) and bridging syndesmophytes (ORadj2.78; 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 andHLA-B*27.
authors.affiliation: Department of Rheumatology, Royal National Hospital for Rheumatic Diseases, Bath, UK.|Department of Rheumatology, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Deepak R
authors.initials: DR
authors.lastname: Jadon
authors.affiliation: Department of Rheumatology, Royal National Hospital for Rheumatic Diseases, Bath, UK.
authors.forename: Raj
authors.initials: R
authors.lastname: Sengupta
authors.affiliation: Department of Pharmacy & Pharmacology, University of Bath, Bath, UK.
authors.forename: Alison
authors.initials: A
authors.lastname: Nightingale
authors.affiliation: Department of Pharmacy & Pharmacology, University of Bath, Bath, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Lindsay
authors.affiliation: Department of Rheumatology, Royal National Hospital for Rheumatic Diseases, Bath, UK.
authors.forename: Eleanor
authors.initials: E
authors.lastname: Korendowych
authors.affiliation: Department of Rheumatology, Royal National Hospital for Rheumatic Diseases, Bath, UK.
authors.forename: Graham
authors.initials: G
authors.lastname: Robinson
authors.affiliation: Department of Mathematical Sciences, University of Bath, Bath, UK.
authors.forename: Amelia
authors.initials: A
authors.lastname: Jobling
authors.affiliation: Department of Mathematical Sciences, University of Bath, Bath, UK.
authors.forename: Gavin
authors.initials: G
authors.lastname: Shaddick
authors.affiliation: Columbia College of Physicians & Surgeons, New York, New York, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Bi
authors.affiliation: Columbia College of Physicians & Surgeons, New York, New York, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Winchester
authors.affiliation: Columbia College of Physicians & Surgeons, New York, New York, USA.
authors.forename: Jon T
authors.initials: JT
authors.lastname: Giles
authors.affiliation: Department of Rheumatology, Royal National Hospital for Rheumatic Diseases, Bath, UK.|Department of Pharmacy & Pharmacology, University of Bath, Bath, UK.
authors.forename: Neil J
authors.initials: NJ
authors.lastname: McHugh
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D000483:Alleles; D001168:Arthritis / Q000000981:diagnostic imaging / Q000209:etiology; D015535:Arthritis, Psoriatic / Q000097:blood / Q000150:complications / Q000000981:diagnostic imaging* / Q000235:genetics*; D002097:C-Reactive Protein / Q000378:metabolism; D003430:Cross-Sectional Studies; D005260:Female; D015796:HLA-B27 Antigen / Q000097:blood / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011446:Prospective Studies; D011859:Radiography; D012307:Risk Factors; D012446:Sacroiliac Joint / Q000000981:diagnostic imaging / Q000473:pathology; D058566:Sacroiliitis / Q000097:blood / Q000000981:diagnostic imaging* / Q000209:etiology; D012720:Severity of Illness Index; D013167:Spondylitis, Ankylosing / Q000097:blood / Q000150:complications / Q000000981:diagnostic imaging* / Q000235:genetics*; D055815:Young Adult
chemical_list: D015796:HLA-B27 Antigen; D002097:C-Reactive Protein
keywords: Ankylosing Spondylitis; Outcomes research; Psoriatic Arthritis; Spondyloarthritis