title: Spinal radiographic progression in patients with ankylosing spondylitis treated with TNF-α blocking therapy: a prospective longitudinal observational cohort study.
abstract: OBJECTIVE
  To evaluate spinal radiographic damage over time and to explore the associations of radiographic progression with patient characteristics and clinical assessments including disease activity in ankylosing spondylitis (AS) patients treated with tumor necrosis factor-alpha (TNF-α) blocking therapy in daily clinical practice.
  
  
  METHODS
  Consecutive outpatients from the Groningen Leeuwarden AS (GLAS) cohort were included based on the availability of cervical and lumbar radiographs before start of TNF-α blocking therapy and after 2, 4, and/or 6 years of follow-up. Clinical data were assessed at the same time points. Radiographs were scored by two independent readers using the modified Stoke AS Spine Score (mSASSS). Spinal radiographic progression in relation to clinical assessments was analyzed using generalized estimating equations.
  
  
  RESULTS
  176 AS patients were included, 58% had syndesmophytes at baseline. Median mSASSS increased significantly from 10.7 (IQR: 4.6-24.0) at baseline to 14.8 (IQR: 7.9-32.8) at 6 years. At the group level, spinal radiographic progression was linear with a mean progression rate of 1.3 mSASSS units per 2 years. Both spinal radiographic damage at baseline and radiographic progression were highly variable between AS patients. Male gender, older age, longer disease duration, higher BMI, longer smoking duration, high CRP, and high ASDAS were significantly associated with syndesmophytes at baseline. Significantly more radiographic progression was seen in patients with versus without syndesmophytes (2.0 vs. 0.5 mSASSS units per 2 years) and in patients >40 versus ≤40 years of age (1.8 vs. 0.7 mSASSS units per 2 years). No longitudinal associations between radiographic progression and clinical assessments were found.
  
  
  CONCLUSIONS
  This prospective longitudinal observational cohort study in daily clinical practice shows overall slow and linear spinal radiographic progression in AS patients treated with TNF-α blocking therapy. At the individual level, progression was highly variable. Patients with syndesmophytes at baseline showed a 4-fold higher radiographic progression rate than patients without syndesmophytes.
authors.affiliation: Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Fiona
authors.initials: F
authors.lastname: Maas
authors.affiliation: Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; Department of Rheumatology, Medical Center Leeuwarden, Leeuwarden, The Netherlands.
authors.forename: Anneke
authors.initials: A
authors.lastname: Spoorenberg
authors.affiliation: Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Brouwer
authors.affiliation: Department of Rheumatology, Medical Center Leeuwarden, Leeuwarden, The Netherlands.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Bos
authors.affiliation: Department of Rheumatology, Medical Center Leeuwarden, Leeuwarden, The Netherlands.
authors.forename: Monique
authors.initials: M
authors.lastname: Efde
authors.affiliation: Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Rizwana N
authors.initials: RN
authors.lastname: Chaudhry
authors.affiliation: Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Nic J G M
authors.initials: NJ
authors.lastname: Veeger
authors.affiliation: Department of Radiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Peter M A
authors.initials: PM
authors.lastname: van Ooijen
authors.affiliation: Department of Radiology, Medical Center Leeuwarden, Leeuwarden, The Netherlands.
authors.forename: Rinze
authors.initials: R
authors.lastname: Wolf
authors.affiliation: Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Hendrika
authors.initials: H
authors.lastname: Bootsma
authors.affiliation: Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Eveline
authors.initials: E
authors.lastname: van der Veer
authors.affiliation: Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; Department of Rheumatology, Medical Center Leeuwarden, Leeuwarden, The Netherlands.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Arends
mesh_terms: D000328:Adult; D018450:Disease Progression; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011859:Radiography; D013167:Spondylitis, Ankylosing / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*
chemical_list: D014409:Tumor Necrosis Factor-alpha