In order to calculate the DAS28, information about some disease variables is needed. The number of swollen joints and tender joints should be assessed using 28-joint counts (tender28 and swollen28). The Erythrocyte Sedimentation Rate (ESR) should be measured (in mm/hour). In addition, the patients general health (GH) or global disease activity measured on a Visual Analogue Scale (VAS) of 100 mm (both are useable for this purpose) must be obtained.

Using this data, the DAS28 can be calculated using the following formula:

DAS28 = 0.56 * sqrt(tender28) + 0.28 * sqrt(swollen28) + 0.70 * ln(ESR) + 0.014 * GH

- This is not a simple formula, but it can easily be calculated using a preprogrammed calculator or other computing devices like our Webculator or programmed excel sheet.

- When no patient assessment of general health or global disease activity is present a DAS28 with 3 variables, or DAS28(3), can be calculated. The formula is mentioned here, together with all other validated DAS versions.

The DAS28 provides you with a number on a scale from 0 to 10 indicating the current activity of the rheumatoid arthritis of your patient. A DAS28 above 5.1 means high disease activity whereas a DAS28 below 3.2 indicates low disease activity. Remission is achieved by a DAS28 lower than 2.6 (comparable to the ARA remission criteria).