title: Hip joint disease in psoriatic arthritis: risk factors and natural history.
abstract: OBJECTIVE
  To determine the natural history of hip joint disease in psoriatic arthritis (PsA) and identify clinical risk factors for its early identification.
  
  
  METHODS
  504 patients with PsA according to ESSG criteria were studied. Mean follow up was 5.7 years (range <1-45). Mean age at onset of psoriasis was 32 years and of PsA, 39 years. The most common pattern of PsA at onset was oligoarticular (49%) and at the latest examination, polyarticular (65%). Sacroiliitis or spondylitis was diagnosed in 94 (18.7%) patients.
  
  
  RESULTS
  32 (6.3%) patients developed psoriatic hip arthropathy, and of these, 26 (81%) also had sacroiliitis or spondylitis. In 7/17 (41%) patients the hip became affected within 1 year after the onset of PsA. Hip disease occurred more often in younger patients. Sex, pattern of peripheral arthritis, duration of psoriasis before arthritis affected the distal interphalangeal joints, dactylitis, or enthesitis were not associated with the risk of hip disease. Seventeen patients were followed up and nine required hip arthroplasty. Sixteen (50%) first had arthroplasty within 5 years after the onset of hip pain.
  
  
  CONCLUSIONS
  Psoriatic hip arthropathy occurs infrequently in PsA and is associated with earlier onset of arthritis and psoriatic spondylitis. Bilateral hip involvement and rapid progression to hip arthroplasty are common.
authors.affiliation: Division of Rheumatology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA. michet.clement@mayo.edu
authors.forename: C J
authors.initials: CJ
authors.lastname: Michet
authors.forename: T G
authors.initials: TG
authors.lastname: Mason
authors.forename: M
authors.initials: M
authors.lastname: Mazlumzadeh
mesh_terms: D000328:Adult; D017668:Age of Onset; D015535:Arthritis, Psoriatic / Q000473:pathology*; D005500:Follow-Up Studies; D006621:Hip Joint / Q000473:pathology*; D006801:Humans; D012307:Risk Factors; D012446:Sacroiliac Joint / Q000473:pathology*; D013166:Spondylitis / Q000473:pathology