What are the Assessment of SpondyloArthritis International Society (ASAS) response criteria?

Updated: Jul 17, 2018
  • Author: Lawrence H Brent, MD; Chief Editor: Herbert S Diamond, MD  more...
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Answer

The ASAS response criteria are used to assess improvement in AS in clinical trials. Each of four domains is scored by the patient on a visual analog scale ranging from 0 to 10. The four domains are as follows:

  • Patient global assessment of disease activity for the past week

  • Patient assessment of back over the past week

  • Function (BASFI)

  • Inflammation (severity and duration of morning stiffness)

An ASAS20 response is defined as an improvement of at least 20% and an absolute improvement of at least 1 unit (on a 0-10 scale) in at least three of four domains, with no worsening of the remaining domain. An ASAS40 response is similar but requires a 40% improvement. An ASAS partial remission is defined as values of less than 2 for all four ASAS20 domains.

ASAS5/6 includes the four domains included in the ASAS20 plus spinal mobility (BASMI) and acute-phase reactants (CRP). An ASAS5/6 response is defined as improvement of at least 20% and an improvement of at least 1 unit in at least five of six domains, with no worsening of the remaining domain.


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