Simplified Disease Activity Index for RA (SDAI)
Assess disease activity in rheumatoid arthritis.
The Simplified Disease Activity Index for Rheumatoid Arthritis (SDAI) is a scoring system that has been validated in both research and clinical settings. It has been shown to have the highest sensitivity and specificity for predicting a physicians' decisions to change DMARD therapy when compared to other scores.
In an observational study, a score ≥15 had the best combination of sensitivity (90%) and specificity (86%) when compared to a clinical decision to change DMARDs because of inadequate control of disease. Remission is defined as an SDAI of <3.3, low disease activity as ≤11, moderate disease activity as ≤26 and high disease activity as >26.
Response to therapy is considered moderate if SDAI decreases by ≥7 and major if decreases by ≥17
SDAI is calculated as follows:
- SDAI = SJC + TJC +PGA + EGA + CRP
- SJC = Swollen Joint Count
- TJC = Tender Joint Count
- PGA = Patient Global Assessment of Disease Activity
- EGA = Evaluator Global Assessment of Disease Activity
- CRP = CRP in mg/dL
Smolen JS, Breedveld FC, Schiff MH, et. al.
Soubrier M et al.