title: Development of new syndesmophytes and bridges in ankylosing spondylitis and their predictors: a longitudinal study.
abstract: BACKGROUND
  Structural damage of the spine in ankylosing spondylitis (AS) is associated with worse physical function and impaired spinal mobility. Knowledge about predictors of new syndesmophyte formation is limited.
  
  
  OBJECTIVE
  To assess the development of new syndesmophytes at the level of individual vertebral bodies and to assess predictors for this development.
  
  
  METHODS
  Clinical and radiological data from 132 patients from the Outcome in Ankylosing Spondylitis International Study for whom complete sets of radiographs were available at baseline and at 2- and 4-year follow-up were used. Univariable and multivariable logistic regression analyses were performed to identify predictors associated with development of new syndesmophytes within 4 years.
  
  
  RESULTS
  At baseline, 81 (61%) patients had syndesmophytes. New syndesmophytes developed in 44 (33%) patients within 2 years and in 63 (48%) patients within 4 years. The RR of developing new syndesmophytes was 5.0 (95% CI 2.5 to 10.2) at 4 years in patients with existing syndesmophytes as compared with patients without. In the univariable analysis, older age, worse functional status, male gender, erythrocyte sedimentation rate and existing syndesmophytes were associated with development of new syndesmophytes at 4 years. In the multivariable logistic regression analysis, only the presence of existing syndesmophytes was a significant predictor (OR 18.72, 95% CI 6.44 to 54.42). When existing syndesmophytes were taken out from the model, age (OR 1.07, 95% CI 1.03 to 1.11) and male gender (OR 3.98, 95% CI 1.47 to 10.77) were statistically significant contributors.
  
  
  CONCLUSIONS
  In AS, patients with existing syndesmophytes are prone to develop new syndesmophytes over time.
authors: Department of Medicine, Division of Rheumatology, Maastricht University Medical Center, The Netherlands. a.van.tubergen@mumc.nl
authors: Astrid
authors: A
authors: van Tubergen
authors: Sofia
authors: S
authors: Ramiro
authors: Désirée
authors: D
authors: van der Heijde
authors: Maxime
authors: M
authors: Dougados
authors: Herman
authors: H
authors: Mielants
authors: Robert
authors: R
authors: Landewé
mesh_terms: D000328:Adult; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging; D018450:Disease Progression; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D054850:Osteophyte / Q000000981:diagnostic imaging / Q000209:etiology*; D011859:Radiography; D012307:Risk Factors; D013167:Spondylitis, Ankylosing / Q000150:complications* / Q000000981:diagnostic imaging; D013997:Time Factors