Simplified versions of the original disease activity score: validation in the BeSt trial

To evaluate three disease activity score (DAS) alternatives without the Ritchie articular index (RAI). To compare the use of patient global assessment (PGA) of disease activity versus global assessment of health (GH) in DAS, DAS alternatives and DAS28.

Data from the BeSt study were used, a treatment strategy trial in early rheumatoid arthritis patients aiming at a DAS ≤2.4. DAS alternatives were DAS 0-1, with the RAI (0-3) reduced to a no-yes (0-1) score, DAS tender joint count 53 (DAS TJC53), with a 0-1 TJC in 53 separate joints and DAS TJC44 in 44 joints. Correlation patterns, mean difference from original DAS, classification differences in disease activity level and patient percentages with radiological damage progression per level were determined for all scores.

In the majority of patients the scores were equal and correlation was high. Mean difference with the DAS at year 1 was -0.03 for DAS 0-1, 0.18 for DAS TJC53 and 0.11 for DAS TJC44. Classification agreement between scores was high (κ year 1 0.76-0.98). Patient percentages with joint damage progression were similar for all scores. DAS, DAS alternative and DAS28 perform similarly using either PGA or GH.

DAS without the RAI perform comparably to the original DAS and may be chosen as alternatives. PGA can replace GH in the DAS, the alternatives and DAS28.