ToolsCalculators
Clinical Disease Activity Index (CDAI) for Rheumatoid Arthritis
RA disease activity from joint counts and global assessments alone, no laboratory data required.
Clinical Disease Activity Index (CDAI) for Rheumatoid Arthritis
Tender joint count (28-joint)
joints
Swollen joint count (28-joint)
joints
Patient global assessment of disease activity
0-10 cm visual analogue scale (0 = very well, 10 = very poor).
cm (0-10)
Evaluator (physician) global assessment of disease activity
0-10 cm visual analogue scale.
cm (0-10)
Complete the fields above to see the result.
When to use
- Bedside or office-based tracking of rheumatoid arthritis disease activity when no acute-phase reactant is immediately available.
- Treat-to-target monitoring, since it can be calculated instantly from the physical exam and two global assessments.
Formula
CDAI = tender joint count (28 joints) + swollen joint count (28 joints) + patient global assessment (0-10 cm VAS) + evaluator global assessment (0-10 cm VAS). Range 0-76. Remission <=2.8, low activity >2.8-10, moderate activity >10-22, high activity >22.
Pearls and pitfalls
- Does not require an ESR or CRP, so it can be calculated during the same visit and is unaffected by acute-phase reactant assay variability.
- Values track closely with SDAI despite omitting CRP, and both correlate well with DAS28.
References
- Aletaha D, Nell VP, Stamm T, et al. Acute phase reactants add little to composite disease activity indices for rheumatoid arthritis: validation of a clinical activity score. Arthritis Res Ther. 2005;7(4):R796-806.
- Aletaha D, Ward MM, Machold KP, et al. Remission and active disease in rheumatoid arthritis: defining criteria for disease activity states. Arthritis Rheum. 2005;52(9):2625-36.