The Simple Disease Activity Index (SDAI) is a composite score used to measure how active rheumatoid arthritis (RA) is at a given time. It’s popular because it’s easy to calculate, sensitive to change, and validated for both clinical practice and research.
SDAI Calculator
Simple Disease Activity Index for Rheumatoid Arthritis (educational use only).
1. Joint counts
Number of tender joints out of the 28-joint assessment.
Number of swollen joints out of the 28-joint assessment.
2. Global assessments (0–10)
0 = no disease activity; 10 = worst possible disease activity (patient’s view).
0 = no disease activity; 10 = worst possible disease activity (clinician’s view).
3. CRP
Use CRP in mg/dL (not mg/L). If you have mg/L, divide by 10.
SDAI score
0.0
Important:
- This calculator is for education only and does not replace rheumatology assessment.
- SDAI should be interpreted together with joint exam, imaging, and the overall clinical picture.
- Never change medication or treatment based solely on this tool.
