DAS28: a useful instrument to monitor infliximab treatment in patients with rheumatoid arthritis

In daily clinical practice, the Disease Activity Score using 28 joint counts (DAS28) is used to monitor the disease activity of rheumatoid arthritis patients treated with disease-modifying anti-rheumatic drugs (DMARDs) and biological agents. This is useful to inform the rheumatologist about whether the treatment is producing the expected effects in an appropriate period of time or whether the treatment should be more intensified.In an article in the present issue, Vander Cruyssen and colleagues investigated which variables can best be measured to evaluate the effect of therapy and the remaining disease activity in daily clinical practice [1]. This study was based on a cohort of 511 patients with active refractory rheumatoid arthritis who were treated with infliximab [2]. Patients who were judged by their physicians to have an insufficient response at week 22 received a dose increase at week 30. According to the authors, the decision to increase the dose was based on clinical judgement, without knowledge of outcome measures such as the DAS28. In their study, the authors found that the DAS28 as a continuous composite index correlated best with the decision to give a dose increase of infliximab, which was used as a surrogate measure of insufficient response. The discriminative capacity of the DAS28 could only slightly be improved by the inclusion of supplemental variables in the regression model. Recalculation of the DAS28 coefficients in a discriminative function obtained similar coefficients and the same discriminative capacity as the original DAS28. For a better understanding of these results, it is informative to know how the Disease Activity Score and the DAS28 were developed back in the 1990s.The DAS28 was developed in a similar way to the Disease Activity Score, but the DAS28 contains reduced, ungraded, joint counts and has different weights [3,4]. The DAS28 was developed in a cohort from an outpatient clinic, using the data from 227 early rheumatoid arthritis p