In rheumatoid arthritis (RA), inflammatory activity cannot be measured using one single variable. For this reason the Disease Activity Score (DAS). has been developed. The DAS is a clinical index of RA disease activity that combines information from swollen joints, tender joints, the acute phase response and general health. The DAS-based European League Against Rheumatism (EULAR) response criteria were developed to measure individual response in clinical trials. The EULAR response criteria classify individual patients as non-, moderate, or good responders, dependent on the extent of change and the level of disease activity reached.