# Disease Activity Score 28 (DAS28)

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The DAS28 (Disease Activity Score 28) is a system developed and validated by the EULAR (European League Against Rheumatism) to measure the progress and improvement of Rheumatoid Arthritis. DAS28 is often used in clinical trials for the development of RA.

DAS28 values range from 2.0 to 10.0 while higher values mean a higher disease activity. A DAS 28 below the value of 2.6 is interpreted as Remission.

The DAS28 is a development of the DAS which is more complex with regards to assessment.

"28" describes the number of different joints including in the measurement:

• proximal interphalangeal joints (10 joints)
• metacarpophalangeal joints (10)
• wrists (2)
• elbows (2)
• shoulders (2)
• knees (2)

When looking at these joints, both the number of joints with tenderness upon touching and swelling are counted. In addition, the erythrocyte sedimentation rate is measured. Also, the patient makes a subjective assessment of disease activity during the preceding 7 days on a scale between 0 and 100, where 0 is "no activity" and 100 is "highest activity possible".

# Definition

With the above mentioned parameters, DAS28 is calculated as:

$DAS28=0.56 \times \sqrt{TEN28} + 0.28 \times \sqrt{SW28} + 0.70 \times \ln(ESR) + 0.014 \times SA$

With:

• TEN28: number of joints with tenderness upon touching
• SW28: number of swollen joints
• ESR: measured erythrocyte sedimentation rate (ESR)
• SA: subjective assessment of disease activity by the patient during the preceding 7 days on a scale betweenn 0 and 100 ("0":no activity, "100": highest activity possible)

The DAS28 provides an absolute indication of RA disease activity on a scale of 0.49 to 9.07

• A DAS28 value >5.1 corresponds to a high disease activity
• A DAS28 value between 3.2 and 5.1 corresponds to a moderate disease activity
• A DAS28 value between 2.6 and 3.2 corresponds to a low disease activity
• A DAS28 value < 2.6 corresponds to remission

Compared to an initial value the disease activity of the patient can be classified as follows:

Current
DAS28
DAS28 decrease from initial value
> 1.2 > 0.6 but ≤ 1.2 ≤ 0.6
≤ 3.2 Inactive Good improvement Moderate improvement No improvement
>3.2 but ≤ 5.1 Moderate Moderate improvement Moderate improvement No improvement
> 5.1 Very active Moderate improvement No improvement No improvement

# References

Last revision by SaschaAhrweiler,07/1/2012