DAS28-CRP For Rheumatoid Arthritis Calculator

Evaluates Rheumatoid Arthritis (RA) activity based on global health, C-reactive protein and joint symptoms.

You can read more about the score and its interpretation in the text below the calculator.

DAS28-CRP is a model that evaluates rheumatoid arthritis disease activity based on 4 variables: one laboratory result, two observations about joint symptoms (tenderness and swelling) and a general health ranking.

The formula is:

DAS28-CRP = 0.56 x sqrt(TJc) + 0.28 x sqrt (SJc) + 0.36 x ln(CRP + 1) + 0.014 x GH + 0.96

Where:

■ TJc = number of tender joints;

■ SJc = number of swollen joints;

■ CRP = c-reactive protein laboratory result;

■ GH = subjective global health assessment.

This is the association between DAS28-CRP and RA disease status is:

■ Scores <2.6: Remission

■ Scores ≥2.6 but ≤3.2: Low activity

■ Scores >3.2 but ≤5.1: Moderate activity

■ Scores >5.1: Active disease

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Steps on how to print your input & results:

1. Fill in the calculator/tool with your values and/or your answer choices and press Calculate.

2. Then you can click on the Print button to open a PDF in a separate window with the inputs and results. You can further save the PDF or print it.

Please note that once you have closed the PDF you need to click on the Calculate button before you try opening it again, otherwise the input and/or results may not appear in the pdf.

DAS28-CRP for rheumatoid arthritis

This is a tool used in routine assessments of RA disease activity and represents the modified version of the original DAS for rheumatoid arthritis.

The difference between the two is that the modified replaces the erythrocyte sedimentation rate (ESR) with the C-reactive protein.

The calculator takes account of the following variables:

■ Tender joint count (TJc);

■ Swollen joint count (SJc);

■ C-reactive protein (CRP);

■ Global health GH (0 – 100), where 0 is very good and 100 is very bad health condition.

The formula used is:

DAS28-CRP = 0.56 x sqrt(TJc) + 0.28 x sqrt (SJc) + 0.36 x ln(CRP + 1) + 0.014 x GH + 0.96

There are 28 joints that are evaluated in the DAS28-CRP:

■ Proximal interphalangeal (10);

■ Metacarpophalangeal (10);

■ Wrists (2);

■ Elbows (2);

■ Shoulders (2);

■ Knees (2).

DAS28-CRP score interpretation

The result values range between 2.0 and 10.0 and the general interpretation rule is that the higher the score, the higher the disease severity.

The following table introduces the interpretation of the results and information about what changes in the result (for each disease activity severity stage) mean.

Present DAS28-CRP	Interpretation	Decrease >1.2	Decrease >0.6 but ≤1.2	Decrease ≤0.6
<2.6	Remission	good improvement	moderate improvement	no improvement
≥2.6 but ≤3.2	Low	good improvement	moderate improvement	no improvement
>3.2 but ≤5.1	Moderate	moderate improvement	moderate improvement	no improvement
>5.1	Active	moderate improvement	no improvement	no improvement

As seen from the table, a cut off score of 2.6 differentiates between remission and low activity arthritis.

Scores such as the DAS28-CRP or DAS28-ESR have shown high reliability in practice, compared to other physician derived scores in monitoring RA.

Rheumatoid arthritis

RA is a progressive autoimmune disease of the joints. On the long term, it results in immobility and deformities in the joints of the fingers, wrists and knees.

RA belongs to the three main types of arthritis along Osteoarthritis (“wear and tear” of the joints) and Psoriatic arthritis, the former caused by aging and obesity whilst the latter associated with the psoriasis skin disease.

Pain in the joints, swelling and stiffness are amongst the most common symptoms. The patient also experiences a sense of general tiredness and 1 in every 5 diagnosed exhibits rheumatoid nodules.

C-reactive protein and erythrocyte sedimentation rate are go to laboratory tests for evidencing inflammation in RA but x-rays and MRI are also used to reveal damage in the joints.