title: Clinical expression, but not disease outcome, may vary according to age at disease onset in psoriatic spondylitis.
abstract: OBJECTIVE
  To investigate whether the clinical expression and disease outcome in psoriatic spondylitis (PsS) may vary according to age at disease onset.
  
  
  METHODS
  This study included 70 patients from a unique outpatient spondylitis clinic followed on a regular basis with a standard protocol. Patients were diagnosed with PsS according to ESSG criteria plus radiographic sacroiliitis (SI). Outcome parameters included: disease activity, functional evaluation, radiological damage, mobility restriction, and enthesitis score. Patients were divided into those with disease onset before 40 years (young-onset PsS) and those with onset over this age (late-onset PsS). Clinical features and outcome parameters were compared between groups.
  
  
  RESULTS
  There were 44 men and 26 women. Thirty-nine (M:F ratio 1.8) patients had disease onset before 40 years and 31 (M:F ratio 1.6) over this age. HLA-B27 correlated with PsS susceptibility (34% vs 7%, RR 6.4, p<0.0004), but it was found over-represented in young-onset PsS compared to late-onset cases (51% vs 13%, p=0.001). Young-onset cases tended to have a higher frequency of family history (26% vs 13%), bilateral SI (62% vs 29%, p=0.013), isolated axial pattern (31% vs 13%), and enthesitis (54% vs 29%, p=0.09). In late-onset PsS there was a higher frequency of unilateral SI (71% vs 38%, p=0.013), polyarthritis (45% vs 23%, p=0.022), and silent axial disease (32% vs 10%, p=0.022). Outcome parameters were similar between groups.
  
  
  CONCLUSIONS
  Clinical picture but not outcome parameters, varies according to age at disease onset in PsS. The correlation between HLA-B27 and young-onset PsS supports the notion that disease susceptibility and disease expression are not driven by the same gene in this entity.
authors.affiliation: Rheumatology Service, Hospital Universitario Central de Asturias, C/ Celestino Villamil s/n, 33006 Oviedo, Spain. queiro@mixmail.com
authors.forename: Ruben
authors.initials: R
authors.lastname: Queiro
authors.forename: Mercedes
authors.initials: M
authors.lastname: Alperi
authors.forename: Alejandra
authors.initials: A
authors.lastname: Lopez
authors.forename: Cristina
authors.initials: C
authors.lastname: Sarasqueta
authors.forename: Jose L
authors.initials: JL
authors.lastname: Riestra
authors.forename: Javier
authors.initials: J
authors.lastname: Ballina
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D015535:Arthritis, Psoriatic / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology; D018450:Disease Progression; D005260:Female; D020022:Genetic Predisposition to Disease; D015796:HLA-B27 Antigen / Q000235:genetics; D006801:Humans; D007596:Joints / Q000473:pathology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010045:Outpatients; D011859:Radiography; D012446:Sacroiliac Joint / Q000000981:diagnostic imaging / Q000473:pathology; D012720:Severity of Illness Index; D013030:Spain / Q000453:epidemiology; D013166:Spondylitis / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology; D055815:Young Adult
chemical_list: D015796:HLA-B27 Antigen