Ankylosing Spondylitis Disease Activity Score

Introduction

The Ankylosing Spondylitis Disease Activity Score (ASDAS) is a new composite index to assess disease activity in Ankylosing Spondylitis (AS). It combines five disease activity variables with only partial overlap, resulting in one single score with better truth (validity), enhanced discriminative capacity and improved sensitivity to change as compared to single-item variables .

The Assessment of SpondyloArthritis international Society (ASAS) membership has selected the ASDAS containing C-reactive protein (CRP, mg/l) as acute phase reactant as the preferred version, and the one with erythrocyte sedimentation rate (ESR, mm/hr) as the alternative version.

The 3 cut-offs selected to separate these states (figure 1) were: <1.3 between “inactive disease” and “low disease activity”, <2.1 between “moderate disease activity” and “high disease activity”, and >3.5 between “high disease activity” and “very high disease activity” (3,4).

Selected cut-offs for improvement scores (figure 2) were: a change ≥1.1 units for “clinically important improvement” and a change ≥2.0 units for “major improvement” (3).

Use the following EVALUATION FORM to evaluate your patient and PRINT THE FORM when the evaluation is completed.

References

1. Lukas C, Landewé R, Sieper J, Dougados M, Davis J, Braun J, van der Linden S, van der Heijde D. Development of an ASAS-endorsed disease activity score (ASDAS) in patients with ankylosing spondylitis. Ann Rheum Dis 2009;68:18-24. (Toll-Free Link)
2. van der Heijde D, Lie E, Kvien TK, Sieper J, van den Bosch F, Listing J, Braun J, Landewé R. ASDAS, a highly discriminatory ASAS-endorsed disease activity score in patients with ankylosing spondylitis. Ann Rheum Dis 2009;68:1811-8. (Toll-Free Link)
3. Machado P, Landewé R, Lie E, Kvien TK, Braun J, Baker D, van der Heijde D. Ankylosing Spondylitis Disease Activity Score (ASDAS): defining cut-off values for disease activity states and improvement scores. Ann Rheum Dis 2011;70:47-53. (Toll-Free Link)
4. Machado PM, Landewé R, van der Heijde DV. Assessment of SpondyloArthritis international Society (ASAS). Ankylosing Spondylitis Disease Activity Score (ASDAS): 2018 update of the nomenclature for disease activity states. Ann Rheum Dis. 2018 Feb 16. doi: 10.1136/annrheumdis-2018-213184. [Epub ahead of print] (Toll-Free Link)
5. Machado P, Landewé R, van der Heijde D. Endorsement of the definitions of disease activity states and improvement scores for the Ankylosing Spondylitis Disease Activity Score (ASDAS): results from the Outcome Measures in Rheumatology (OMERACT) 10 conference. J Rheumatol 2011;38:1502-6.