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DAS28 (ESR and CRP)

Measures rheumatoid arthritis activity using 28 tender and swollen joints, an acute-phase reactant and patient global assessment.

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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

DAS28-ESR/Prevoo 1995 and DAS28-CRP/Wells 2009; 28 joints; CRP intercept 0.96

The 1995 DAS28 was developed for rheumatoid arthritis activity, using a 28-joint count and comparisons with rheumatologists’ clinical assessments. The CRP variant is not automatically equivalent to the ESR variant; the formula, units and cutoffs must match the source and edition used.

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 health assessment (visual scale) · mm
Erythrocyte sedimentation rate (ESR) · mm/h
C-reactive protein (CRP) · mg/L

5/5 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.

DAS28-ESR = 0.56 × √(tender) + 0.28 × √(swollen) + 0.70 × ln(ESR) + 0.014 × global assessment.

DAS28-CRP = 0.56 × √(tender) + 0.28 × √(swollen) + 0.36 × ln(CRP + 1) + 0.014 × global assessment + 0.96 (CRP in mg/L).

References

Identifier: das28

Original clinical content: Brazilian Portuguese.

Method version

DAS28-ESR/Prevoo 1995 and DAS28-CRP/Wells 2009; 28 joints; CRP intercept 0.96

das28@native-2026-10-03+aff7e9d8589f

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 (5)

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): 4
Patient global health assessment (visual scale): 50 mm
Erythrocyte sedimentation rate (ESR): 25 mm/h

{
  "tjc": 4,
  "sjc": 4,
  "gh": 50,
  "vhs": 25
}

Expected result

{
  "esr": 4.633
}

Actual result

{
  "esr": 4.63321307740774,
  "crp": null
}

Case 2

reference-002

Inputs

Tender joints (out of 28): 0
Swollen joints (out of 28): 0
Patient global health assessment (visual scale): 10 mm
Erythrocyte sedimentation rate (ESR): 10 mm/h

{
  "tjc": 0,
  "sjc": 0,
  "gh": 10,
  "vhs": 10
}

Expected result

{
  "esr": 1.752
}

Actual result

{
  "esr": 1.751809565095832,
  "crp": null
}

Case 3

reference-003

Inputs

Tender joints (out of 28): 16
Swollen joints (out of 28): 9
Patient global health assessment (visual scale): 80 mm
Erythrocyte sedimentation rate (ESR): 64 mm/h

{
  "tjc": 16,
  "sjc": 9,
  "gh": 80,
  "vhs": 64
}

Expected result

{
  "esr": 7.111
}

Actual result

{
  "esr": 7.11121815835177,
  "crp": null
}

Case 4

reference-004

Inputs

Tender joints (out of 28): 4
Swollen joints (out of 28): 4
Patient global health assessment (visual scale): 50 mm
C-reactive protein (CRP): 9 mg/L

{
  "tjc": 4,
  "sjc": 4,
  "gh": 50,
  "pcr": 9
}

Expected result

{
  "crp": 4.169
}

Actual result

{
  "esr": null,
  "crp": 4.168930633477856
}

Case 5

reference-005

Inputs

Tender joints (out of 28): 4
Swollen joints (out of 28): 4
Patient global health assessment (visual scale): 50 mm

{
  "tjc": 4,
  "sjc": 4,
  "gh": 50
}

Expected result

{
  "error": true
}

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.