title: The link between enthesitis and arthritis in psoriatic arthritis: a switch to a vascular phenotype at insertions may play a role in arthritis development.
abstract: OBJECTIVE
  Subclinical enthesopathy is recognised in both psoriasis and psoriatic arthritis (PsA). This study used ultrasonography with power Doppler (PD) to test the hypothesis that subclinical enthesopathy in PsA was associated with an 'inflammatory' or vascular phenotype compared to that seen in psoriasis.
  
  
  METHODS
  100 patients with a mean age of 46.3 years (SD 15) (42 with psoriasis and 58 with PsA) and 23 matched healthy controls (HC) from two centres were included. 1230 lower limb entheses were scanned by ultrasonographers blinded to clinical details. Both inflammatory and chronic features of enthesopathy were scored.
  
  
  RESULTS
  Psoriasis patients (with or without arthritis) were more likely to express a vascular phenotype, with higher inflammation-related enthesopathy scores than HC (for inflammation p<0.0001, for chronicity p=0.02, for total ultrasound scores p<0.0001). The PsA patients had higher ultrasound enthesopathy scores than psoriasis patients (inflammation p=0.04, chronicity p=0.02) and HC (inflammation p<0.0001, chronicity p=0.003). When symptomatic entheses were excluded, PsA patients still had higher PD scores than psoriasis patients (p=0.003). Doppler positivity in at least one entheseal site was observed more frequently in PsA (21/58, 36.2%) versus psoriasis (4/42, 9.5%; p=0.002).
  
  
  CONCLUSIONS
  This study shows that the ultrasound appearances of subclinical enthesitis in psoriasis differ from the subclinical enthesitis in PsA, with PsA patients having more PD. This is suggestive of a more inflammatory or vascular process in PsA, and offers potentially novel insights into the progression from skin to joint disease in psoriasis.
authors.affiliation: Unit of Rheumatology, Medeniyet University, Goztepe Training and Research Hospital, Istanbul, Turkey.
authors.forename: Sibel Z
authors.initials: SZ
authors.lastname: Aydin
authors.forename: Zoe R
authors.initials: ZR
authors.lastname: Ash
authors.forename: Ilaria
authors.initials: I
authors.lastname: Tinazzi
authors.forename: Concepción
authors.initials: C
authors.lastname: Castillo-Gallego
authors.forename: Chung
authors.initials: C
authors.lastname: Kwok
authors.forename: Caroline
authors.initials: C
authors.lastname: Wilson
authors.forename: Mark
authors.initials: M
authors.lastname: Goodfield
authors.forename: Paolo
authors.initials: P
authors.lastname: Gisondi
authors.forename: Ai Lyn
authors.initials: AL
authors.lastname: Tan
authors.forename: Helena
authors.initials: H
authors.lastname: Marzo-Ortega
authors.forename: Paul
authors.initials: P
authors.lastname: Emery
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Wakefield
authors.forename: Dennis G
authors.initials: DG
authors.lastname: McGonagle
mesh_terms: D000328:Adult; D015535:Arthritis, Psoriatic / Q000150:complications / Q000000981:diagnostic imaging*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D035002:Lower Extremity / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011565:Psoriasis / Q000150:complications / Q000000981:diagnostic imaging; D012216:Rheumatic Diseases / Q000150:complications / Q000000981:diagnostic imaging*; D018608:Ultrasonography, Doppler