SDAI (Simplified Disease Activity Index, rheumatoid arthritis)
Simplified Disease Activity Index for RA: CDAI plus CRP in mg/dL (0-86) (Smolen 2003).
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Swollen-joint count
- 6
- Tender-joint count
- 8
- Patient global assessment
- 3
- Physician global assessment
- 2
- CRP
- 1.5 mg/dL
Result: SDAI 20.5/86 — moderate disease activity (> 11–26).
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Bands
- remission ≤ 3.3, low ≤ 11, moderate ≤ 26, high > 26.
What you enter
- Swollen-joint count (0-28)
- Tender-joint count (0-28)
- Patient global assessment (0-10 cm VAS)
- Physician global assessment (0-10 cm VAS)
- CRP
How this is calculated
- Formula
- SDAI = SJC28 + TJC28 + patient global + physician global + CRP (mg/dL), total 0–86. CRP in mg/L is 10× larger — divide by 10 first.
Smolen JS, Breedveld FC, Schiff MH, et al. A simplified disease activity index for rheumatoid arthritis for use in clinical practice. Rheumatology (Oxford). 2003;42(2):244-257. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.