ToolsCalculators
Ankylosing Spondylitis Disease Activity Score with CRP (ASDAS-CRP)
Composite disease-activity index for axial spondyloarthritis using CRP.
Ankylosing Spondylitis Disease Activity Score with CRP (ASDAS-CRP)
Back pain, last week
0 = none, 10 = worst possible (BASDAI question 2).
/10
Duration of morning stiffness, last week
0 = none, 10 = worst possible (BASDAI question 6).
/10
Patient global assessment of disease activity, last week
0 = not active, 10 = very active.
/10
Peripheral pain/swelling, last week
0 = none, 10 = worst possible (BASDAI question 3).
/10
CRP
mg/L
Complete the fields above to see the result.
When to use
- Quantifying disease activity in axial spondyloarthritis (ankylosing spondylitis or non-radiographic axSpA) for monitoring and treatment decisions.
- Preferred over BASDAI when a recent CRP is available, since it incorporates an objective acute-phase marker.
Formula
ASDAS-CRP = 0.12 x back pain + 0.06 x duration of morning stiffness + 0.11 x patient global assessment + 0.07 x peripheral pain/swelling + 0.58 x Ln(CRP[mg/L]+1). Each patient-reported item is scored 0-10 (NRS).
Pearls and pitfalls
- Cut-offs: <1.3 inactive, 1.3 to <2.1 moderate, 2.1 to <3.5 high, >=3.5 very high disease activity.
- A CRP of exactly 0 mg/L should be entered as the assay's lower limit if it is reported as "<X"; do not leave the field blank.
References
- Lukas C, Landewé R, Sieper J, et al. Development of an ASAS-endorsed disease activity score (ASDAS) in patients with ankylosing spondylitis. Ann Rheum Dis. 2009;68(1):18-24.
- Machado P, Landewé R, Lie E, et al. Ankylosing Spondylitis Disease Activity Score (ASDAS): defining cut-off values for disease activity states and improvement scores. Ann Rheum Dis. 2011;70(1):47-53.