What Is DAS28?

Monitoring Disease Activity in Rheumatoid Arthritis Patients

Doctor examining a wrist.
BSIP/UIG/Getty Images

DAS28, a modified version of the original DAS, is a quantitative measure of disease activity used to monitor the treatment of rheumatoid arthritis. DAS28, which stands for "disease activity score," is calculated using a formula that includes the number of tender joints and swollen joints (28 joints maximum). DAS28 is not only useful for assessing patients in clinical practice, but for clinical trials as well.

There are several versions of DAS, but they all measure disease burden using patient global health (patient self-assessment), tender joint counts and swollen joint counts (up to 28), and the ESR (erythrocyte sedimentation rate) or CRP (C-reactive protein). The DAS can be calculated using a specific program or calculator -- or by going to a website, http://www.das-score.nl/das28/en/. If you have an iPhone or other smart phone, there are DAS apps available.

History of DAS

The beginning of DAS is considered circa 1983. The original DAS included the Ritchie articular index, the 44 swollen-joint count, the ESR (erythrocyte sedimentation rate) and a general health assessment on a visual analogue scale.

Usefulness in Clinical Practice

Decisions about treatment can be based on current DAS28 values or on changes in DAS28 values compared to values before treatment started. The DAS28 high and low disease activity thresholds have been validated.

There also is a clearly defined relationship between the mean DAS during a certain period and the amount of x-ray damage that a patient develops within that time period.

Scoring of DAS28

After the complex calculation has been made:

DAS28 >5.1 = high disease activity
DAS28 <3.2 = low disease activity
DAS28 <2.6 = remission

Other versions of DAS28 exist that allow CRP to be used instead of ESR -- or that allow omission of either CRP or ESR. Check out the DAS calculator options.

The Bottom Line

You may never hear your rheumatologist refer specifically to your DAS28 score. I have never heard those words spoken in my doctor's office. But, most assuredly, your doctor is paying attention to the joint counts, sedimentation rate, and CRP -- and comparatively from one office visit to the next. Don't be shy. Ask your doctor about your DAS28 if it hasn't been mentioned. According to the National Rheumatoid Arthritis Society, "A persistently high score has been found to increase the likelihood of progressive joint damage, even in patients who appear to be doing well. Therefore, although not a perfect measure of disease activity, it might be useful to ask ‘What’s my DAS28?’ next time you visit the rheumatology department."

Sources:

Disease Activity Score. Rheumatoid Arthritis: Early Diagnosis and Treatment. Cush, Weinblatt, and Kavanaugh. Third Edition. Published by Professional Communications, Inc. (2010).

The DAS28 Score. National Rheumatoid Arthritis Society. Last reviewed 5/5/2014.
http://www.nras.org.uk/the-das28-score

Continue Reading