ToolsCalculators
Simple Disease Activity Index (SDAI) for Rheumatoid Arthritis
Simple Disease Activity Index (SDAI) 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)
C-reactive protein
Enter as mg/dL (upper limit for scoring purposes is 10 mg/dL).
mg/dL
Complete the fields above to see the result.
When to use
- Quantifying rheumatoid arthritis disease activity and monitoring treat-to-target response when a CRP is available.
- Cross-checking CDAI when the acute-phase response is discordant with the clinical joint findings.
Formula
SDAI = tender joint count (28 joints) + swollen joint count (28 joints) + patient global assessment (0-10 cm VAS) + evaluator global assessment (0-10 cm VAS) + CRP (mg/dL, capped for scoring at 10). Range 0-86. Remission <=3.3, low activity >3.3-11, moderate activity >11-26, high activity >26.
Pearls and pitfalls
- CRP contributes only a small amount to the total score compared with the joint counts and global assessments.
- Uses the same 4 clinical components as CDAI plus CRP; CDAI can be used interchangeably when CRP is unavailable.
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.