PUBLIC LIBRARY / CALCULATOR

CDAI and SDAI

Composite rheumatoid arthritis activity indices using simple sums; CDAI needs no laboratory tests and can be used during the consultation.

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Check the population, units and version. The result shows the formula or classification; it does not make an automatic treatment decision.

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Method · Limits of application

SDAI/Smolen 2003 and CDAI/Aletaha 2005: 28 joints; global assessments 0–10; CRP mg/dL only in SDAI

The 2003 SDAI was studied for rheumatoid arthritis activity and treatment response, with a 28-joint count, global assessments on a 0–10 scale and CRP in mg/dL. It is not a standalone diagnostic test for rheumatoid arthritis. CDAI without CRP and the activity cutoffs belong to their respective variants and must be checked in the specific sources.

Conditions of use

Check the population, units, inclusion and exclusion criteria, and version in the original source. A result alone does not establish a diagnosis, discharge decision or prescription.

Documented parameters

Tender joints (out of 28)
Swollen joints (out of 28)
Patient global assessment · 0 to 10
Physician global assessment · 0 to 10
C-reactive protein (for SDAI) · mg/dL

4/4 reference cases checked. Numerical tests are not clinical validation.

Sources and documentation

Documented formula

Transcribed from the source or a recorded revision; this is not a clinical recommendation.

CDAI = tender joints (28) + swollen joints (28) + patient global assessment (0–10) + physician global assessment (0–10). Range 0–76.

SDAI = CDAI + CRP (mg/dL). Range 0 to approximately 86.

References

Identifier: cdai-sdai

Original clinical content: Brazilian Portuguese.

Method version

SDAI/Smolen 2003 and CDAI/Aletaha 2005: 28 joints; global assessments 0–10; CRP mg/dL only in SDAI

cdai-sdai@native-2026-10-03+791dbf3d2fc9

Source for the active edition

The bibliographic edition identifies the source. By itself, it proves neither full conformity of the formula nor clinical approval.

Synthetic cases checked (4)

Synthetic cases for checking the implementation, with no patient data.

Case 1

reference-001

Inputs

Tender joints (out of 28): 4
Swollen joints (out of 28): 3
Patient global assessment: 5 0 to 10
Physician global assessment: 4 0 to 10
C-reactive protein (for SDAI): 1.2 mg/dL

{
  "tjc": 4,
  "sjc": 3,
  "pga": 5,
  "ega": 4,
  "pcr": 1.2
}

Expected result

{
  "cdai": 16,
  "sdai": 17.2
}

Actual result

{
  "cdai": 16,
  "sdai": 17.2
}

Case 2

reference-002

Inputs

Tender joints (out of 28): 1
Swollen joints (out of 28): 0
Patient global assessment: 1 0 to 10
Physician global assessment: 0.5 0 to 10

{
  "tjc": 1,
  "sjc": 0,
  "pga": 1,
  "ega": 0.5
}

Expected result

{
  "cdai": 2.5
}

Actual result

{
  "cdai": 2.5,
  "sdai": null
}

Case 3

reference-003

Inputs

Tender joints (out of 28): 3
Swollen joints (out of 28): 2
Patient global assessment: 3 0 to 10
Physician global assessment: 2 0 to 10

{
  "tjc": 3,
  "sjc": 2,
  "pga": 3,
  "ega": 2
}

Expected result

{
  "cdai": 10
}

Actual result

{
  "cdai": 10,
  "sdai": null
}

Case 4

reference-004

Inputs

Tender joints (out of 28): 10
Swollen joints (out of 28): 8
Patient global assessment: 7 0 to 10
Physician global assessment: 6 0 to 10

{
  "tjc": 10,
  "sjc": 8,
  "pga": 7,
  "ega": 6
}

Expected result

{
  "cdai": 31
}

Actual result

{
  "cdai": 31,
  "sdai": null
}

Code and reproducibility

This tool’s code on GitHub

Download code and tests

Sources, version and reproduction instructions

The code tests are technical checks. Clinical approval and professional translation review are recorded separately.

Relationship with cancer research

General context — relationship to be defined

A resource for general clinical contexts. This edition does not assign a specific oncological relationship; selecting it for a study requires a justified question, population and purpose.