DAS-28 Score Interpretation and Application

Components and Calculation

The DAS-28 score is a composite measure that combines a 28-joint tender count, a 28-joint swollen count, an acute-phase reactant, and patient global assessment of disease activity, calculated using a complex weighted formula, as recommended by the American College of Rheumatology 1, 2
The DAS28 includes the following elements: 28 tender joint count, 28 swollen joint count, acute-phase reactant, and patient global assessment of disease activity, with the 28 tender joint count weighted more heavily than swollen joints in the calculation 1, 2
The calculation requires differential weighting of individual components and is more complex than simple arithmetic addition, typically requiring a calculator, according to the European League Against Rheumatism 1, 2

DAS28 scores are interpreted as follows: Remission (≤2.4), Low disease activity (>2.4 to ≤3.2), with the American College of Rheumatology recommending a target of ≤2.4 for improved RA outcomes 1, 2, 3
Treating to a DAS28 target of ≤2.4 has been shown to improve RA outcomes, with a strength of evidence rated as high, according to the American College of Rheumatology 1, 2

DAS28-CRP and DAS28-ESR are NOT interchangeable and should not use the same cut-off values, with the European League Against Rheumatism recommending separate interpretation of each score 1, 2
ESR contributes approximately 15% of the information in DAS28-ESR, and newer biologic agents targeting specific inflammatory cytokines may disproportionately affect ESR and CRP, potentially deflating the composite score, according to the American College of Rheumatology 1, 2
The inclusion of acute-phase reactants introduces complexity that can lead to misclassification, particularly in high ESR states with few active joints or low ESR states where remission criteria may be met despite patients having a significant number of swollen joints, with a strength of evidence rated as moderate, according to the European League Against Rheumatism 1, 2

DAS28 remission criteria are less stringent than SDAI (≤3.3) or CDAI (≤2.8), meaning DAS28 may classify patients as being in remission when other measures would not, with the American College of Rheumatology recommending consideration of multiple measures for accurate assessment 1, 2, 4
Unlike SDAI and CDAI, which use simple arithmetic addition, DAS28 requires complex differential weighting, and SDAI is the most sensitive and specific for predicting clinical decisions to change DMARDs, according to the European League Against Rheumatism 1, 2

The DAS28 score has several disadvantages, including requiring laboratory results (ESR or CRP), which delays point-of-care calculation, and complex calculation requiring a calculator or computer, with the American College of Rheumatology recommending implementation of electronic patient records and web-based monitoring systems to facilitate calculation 1, 2
Examiner-dependent joint counts may be unreliable if the assessor changes, and logistical barriers have delayed widespread adoption in smaller practice settings, with the European League Against Rheumatism recommending standardization of assessment methods to minimize variability 1, 2