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Responsiveness of the Ankylosing Spondylitis Disease Activity Score (ASDAS) and clinical and MRI measures of disease activity in a 1-year follow-up study of patients with axial spondyloarthritis treated with tumour necrosis factor α inhibitors
  1. Susanne Juhl Pedersen1,
  2. Inge Juul Sørensen2,
  3. Kay-Geert A Hermann3,
  4. Ole Rintek Madsen4,
  5. Niels Tvede5,
  6. Michael Sejer Hansen6,
  7. Gorm Thamsborg7,
  8. Lis Smedegaard Andersen8,
  9. Ole Majgaard2,
  10. Anne Gitte Loft9,
  11. Jon Erlendsson10,
  12. Karsten Asmussen11,
  13. Julia S Johansen6,
  14. Anne Grethe Jurik12,
  15. Jakob Møller13,
  16. Maria Hasselquist13,
  17. Dorrit Mikkelsen14,
  18. Thomas Skjødt15,
  19. Annette Hansen5,16,
  20. Mikkel Østergaard2,6
  1. 1Department of Rheumatology, Gentofte University Hospital, Denmark
  2. 2Department of Rheumatology, Hvidovre University Hospital, Copenhagen, Denmark
  3. 3Department of Radiology, Charité University Hospital, Berlin, Germany
  4. 4Department of Rheumatology, Gentofte University Hospital, Copenhagen, Denmark
  5. 5Department of Rheumatology, Rigshopitalet University Hospital, Copenhagen, Denmark
  6. 6Department of Rheumatology, Herlev University Hospital, Copenhagen, Denmark
  7. 7Department of Rheumatology, Glostrup University Hospital, Copenhagen, Denmark
  8. 8Rheumatism Hospital, University of Southern Denmark, Graasten, Denmark
  9. 9Department of Rheumatology, Vejle Hospital, Vejle, Denmark
  10. 10Department of Rheumatology, Horsens Hospital, Horsens, Denmark
  11. 11Department of Rheumatology, Bispebjerg University Hospital, Copenhagen, Denmark
  12. 12Department of Radiology, Århus University Hospital, Århus, Denmark
  13. 13Department of Radiology, Herlev University Hospital, Copenhagen, Denmark
  14. 14Department of Radiology, Aabenraa Hospital, Aabenraa, Denmark
  15. 15Department of Radiology, Vejle Hospital, Vejle, Denmark
  16. 16The DANBIO Database, Department of Rheumatology, Hvidovre Hospital, Copenhagen, Denmark
  1. Correspondence to Susanne Juhl Pedersen, Department of Rheumatology, C Post 535, Gentofte University Hospital, Niels Andersens Vej 65, DK-2900 Hellerup, Denmark; susanne_juhl_ped{at}


Objectives To investigate construct validity and responsiveness of the novel ankylosing spondylitis (AS) disease activity score (ASDAS) in patients with spondyloarthritis (SpA).

Methods In a 46-week prospective longitudinal multicentre study of 60 patients with SpA (80% men, median age 40 years (range 21–62)) treated with tumour necrosis factor α (TNFα) inhibitors (infliximab, n=41; etanercept, n=13; adalimumab, n=6), the responsiveness of ASDAS, conventional clinical measures of disease activity and treatment response and the Berlin MRI sacroiliac joint (SIJ) and lumbar spine inflammation scores were compared.

Results After 22 weeks, 58.3% of the patients were clinical responders (50% or 20 mm reduction in the Bath AS Disease Activity Index (BASDAI)). At baseline, clinical responders had significantly higher median (range) ASDAS than non-responders (4.15 (1.98–6.04) vs 2.99 (2.05–6.19), p=0.008). Changes in ASDAS correlated with changes in clinical measures of disease activity (including BASDAI (ρ=0.76) and C-reactive protein (CRP) (0.79)), MRI SIJ inflammation (0.46) and MRI total inflammation scores (0.34). Patients with higher BASDAI or Assessment of SpondyloArthritis International Society (ASAS) responses obtained more profound reductions in ASDAS. ASDAS had the highest responsiveness with an effect size of 2.04 and a standardised response mean of 1.45, whereas BASDAI (effect size 1.86; standardised response mean 1.36) and CRP (effect size 0.63; standardised response mean 0.70) were less responsive. Linear regression showed that a change in BASDAI of 20 mm or 50% corresponded to a change in ASDAS of 1.38 and 1.95, respectively.

Conclusion ASDAS demonstrates construct validity and high responsiveness during treatment with TNFα inhibitors in patients with SpA. The proposed thresholds for disease activity and treatment response need further validation.

Trial registration number NCT00133315.

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  • Funding SJP's salary during her position as a PhD student was financed by the Faculty of Health Sciences, University of Copenhagen, Denmark. Abbott Denmark printed and distributed the case report forms used in the study.

  • Competing interests None.

  • Ethics approval The study was approved by the regional scientific ethical committee (reference number H-KF-02–050/04) and conducted in accordance with the Helsinki II declaration.

  • Provenance and peer review Not commissioned; externally peer reviewed.