title: Clinical outcomes and progression to orthopedic surgery in juvenile- versus adult-onset ankylosing spondylitis.
abstract: OBJECTIVE
  Juvenile- and adult-onset ankylosing spondylitis (AS) are subtypes of AS that may have different clinical outcomes. We compared cohorts of juvenile-onset AS and adult-onset AS in terms of clinical characteristics, clinical outcomes, proceeding to AS-related orthopedic surgery, and type of orthopedic surgery.
  
  
  METHODS
  A retrospective cohort study was conducted of all AS patients attending a teaching hospital. Demographics, clinical parameters, and history of AS-related orthopedic surgery to the spine, root, or peripheral joints were recorded. Differences between surgery for juvenile- and adult-onset AS patients, and effects of covariates were assessed using logistic regression and survival analyses.
  
  
  RESULTS
  A total of 553 AS patients were studied: 162 juvenile-onset AS and 391 adult-onset AS cases. After adjusting for significant covariates, adult-onset AS cases were less likely to proceed to surgery (odds ratio [OR] 0.31, P < 0.001), have a hip procedure (resurfacing or arthroplasty; OR 0.374, P = 0.001), and have hip arthroplasty (OR 0.43, P = 0.01). Significant differences were also observed when comparing Kaplan-Meier survival curves (P = 0.001) and using Cox proportional hazards regression (P = 0.002). A history of smoking was not associated with surgery. AS cases with older age at symptom onset were far less likely to have surgery than those with younger onset, in a nonlinear manner.
  
  
  CONCLUSIONS
  Juvenile-onset AS cases are more likely than adult-onset AS cases to proceed to hip arthroplasty, but equally likely to have hip resurfacing and hip arthroplasty revision/re-revisions. Smoking was not associated with the risk of orthopedic surgery. Orthopedic surgery was unlikely after 40 years of disease in both subsets.
authors.affiliation: Royal National Hospital for Rheumatic Diseases, Bath, UK.
authors.forename: Deepak R
authors.initials: DR
authors.lastname: Jadon
authors.forename: Gavin
authors.initials: G
authors.lastname: Shaddick
authors.forename: Amelia
authors.initials: A
authors.lastname: Jobling
authors.forename: Athimalaipet V
authors.initials: AV
authors.lastname: Ramanan
authors.forename: Raj
authors.initials: R
authors.lastname: Sengupta
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D019644:Arthroplasty, Replacement, Hip; D016009:Chi-Square Distribution; D002648:Child; D018450:Disease Progression; D018572:Disease-Free Survival; D004739:England / Q000453:epidemiology; D005260:Female; D006784:Hospitals, Teaching; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008297:Male; D017711:Nonlinear Dynamics; D016017:Odds Ratio; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013167:Spondylitis, Ankylosing / Q000175:diagnosis / Q000453:epidemiology / Q000601:surgery*; D013997:Time Factors; D055815:Young Adult