SDAI Score Calculator

SDAI Score Calculator for Rheumatology. Index remission is at or below 3.3; low activity is above 3.3 through 11, moderate above 11 through 26, and high above 26. An unrounded value of 3.305 therefore belongs to low activity, without a decimal gap.

For shared guidance on choosing a tool and documenting results, read the clinical calculator workflow.

How this calculator works

SDAI is the sum of the two 28-joint counts, the two global assessments and CRP in mg/dL. This is a direct sum: no logarithm, weighting coefficient or ESR substitution is included.

When to use this calculator

Monitor activity in established rheumatoid arthritis with contemporaneous examination and laboratory data. Confirm that a 100-mm global assessment has been divided by ten and that a laboratory CRP reported in mg/L has also been divided by ten.

Inputs used

  • Whole-number tender and swollen counts from 28 joints, patient and evaluator global scores each 0-10 cm, and CRP specifically in mg/dL.

Clinical interpretation

Index remission is at or below 3.3; low activity is above 3.3 through 11, moderate above 11 through 26, and high above 26. An unrounded value of 3.305 therefore belongs to low activity, without a decimal gap.

Worked example

Tender count two, swollen count one, patient global three, evaluator global two and CRP 15 mg/L give 2 + 1 + 3 + 2 + 1.5 = 9.5. Adding 15 instead would incorrectly yield 23 and change the activity category.

Limitations and safety notes

Feet and ankles are outside the 28-joint assessment. Infection can elevate CRP and noninflammatory pain can elevate global ratings. An index band is not a diagnosis, a universal medication instruction or proof that inflammation is absent everywhere.

References

  • https://pubmed.ncbi.nlm.nih.gov/12595618/
  • https://pmc.ncbi.nlm.nih.gov/articles/PMC4028066/

Editorial review and citation methodology

Maintained by the Quick Medical Calculator Editorial Team. Content record date: September 9, 2026. A content date is not evidence of independent clinical review. Individual clinical sign-off is not recorded on this page.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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