title: Evolution of radiographic damage in ankylosing spondylitis: a 12 year prospective follow-up of the OASIS study.
abstract: OBJECTIVE
  To describe the evolution of radiographic abnormalities of the spine in patients with ankylosing spondylitis (AS).
  
  
  METHODS
  Patients with AS were followed prospectively with 2 yearly radiographs for 12 years. The modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) was scored by two readers (R1 and R2). New syndesmophytes at uninvolved vertebral corners were computed. Radiographic progression was investigated using generalised estimating equations.
  
  
  RESULTS
  809 radiographs (presenting 520 at 2 yearly intervals) from 186 patients (70% men, mean age 43 (SD 12) years, mean 20 (SD 12) years since symptom onset and 83% HLA-B27 positive) were included. Mean mSASSS at baseline was 11.6 (16.2). While the course of progression in individual patients was highly variable, and still occurred in patients with decades of symptom duration, mean 2 year progression was 2.0 (3.5) mSASSS units. Over the entire follow-up, at least one new syndesmophyte was found in 55% (R1) and 63% (R2) of patients (38% (R1) and 39% (R2) of all intervals). In 24% of patients (39% of intervals), there was no progression. A progression ≥5 mSASSS units occurred in 22% of patients (or in 12% of intervals). At the group level, a linear time course model fitted the data best, with a constant rate over the entire 12 year interval of 0.98 mSASSS units/year. Radiographic progression occurred significantly faster in men, in HLA-B27 positive patients and in patients with a baseline mSASSS≥10.
  
  
  CONCLUSIONS
  Long term radiographic progression in AS is highly variable in the individual patient, more severe in HLA-B27 positive men and still occurs after decades of disease. At the group level, however, progression in AS follows an approximately linear course.
authors: Department of Clinical Immunology and Rheumatology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands Department of Rheumatology, Hospital Garcia de Orta, Almada, Portugal.
authors: Sofia
authors: S
authors: Ramiro
authors: Department of Medicine, Division of Rheumatology, Maastricht University Medical Centre, Maastricht, The Netherlands School for Public Health and Primary Care (CAPHRI), University of Maastricht, Maastricht, The Netherlands.
authors: Carmen
authors: C
authors: Stolwijk
authors: Department of Medicine, Division of Rheumatology, Maastricht University Medical Centre, Maastricht, The Netherlands School for Public Health and Primary Care (CAPHRI), University of Maastricht, Maastricht, The Netherlands.
authors: Astrid
authors: A
authors: van Tubergen
authors: Department of Rheumatology, Leiden University Medical Centre, Leiden, The Netherlands.
authors: Désirée
authors: D
authors: van der Heijde
authors: Rheumatology B Department, Paris-Descartes University, Cochin Hospital, Paris, France.
authors: Maxime
authors: M
authors: Dougados
authors: Department of Rheumatology, University of Ghent, Ghent, Belgium.
authors: Filip
authors: F
authors: van den Bosch
authors: Department of Clinical Immunology and Rheumatology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands Department of Rheumatology, Atrium Medical Centre, Heerlen, The Netherlands.
authors: Robert
authors: R
authors: Landewé
mesh_terms: D000328:Adult; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D015796:HLA-B27 Antigen / Q000235:genetics; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011859:Radiography; D012720:Severity of Illness Index; D013131:Spine / Q000000981:diagnostic imaging*; D013167:Spondylitis, Ankylosing / Q000000981:diagnostic imaging* / Q000235:genetics
chemical_list: D015796:HLA-B27 Antigen
keywords: ankylosing spondylitis; mSASSS; outcome measures; radiographic damage; spondyloarthritis; syndesmophytes