Performances of Clinical Disease Activity Index (<scp>CDAI</scp>) and Simplified Disease Activity Index (<scp>SDAI</scp>) appear to be better than the gold standard Disease Assessment Score (<scp>DAS</scp>‐28‐<scp>CRP</scp>) to assess rheumatoid arthritis patients

Abstract

Abstract Background/Purpose To compare the performance of Disease Assessment Score of 28 joints – C‐reactive protein ( DAS ‐28‐ CRP ), Clinical Disease Activity Index ( CDAI ) and Simplified Disease Activity Index ( SDAI ) composite measures to assess status of patients with rheumatoid arthritis ( RA ) on methotrexate, versus DAS ‐28 CRP as the gold standard. Methods One hundred and thirty‐five patients with RA as per the 2010 American College of Rheumatology/European League Against Rheumatism criteria were included in the prospective study. The disease activity was assessed at baseline and at every 6 weeks for 24 weeks, by DAS ‐28‐ CRP , CDAI and SDAI . Patients were divided into groups of remission, low, moderate and high activity on the basis of predefined cut‐offs for DAS ‐28‐ CRP , CDAI and SDAI . A Spearman correlation between composite measures and inter‐group comparison of the measures was performed. Results There was an excellent positive correlation between DAS ‐28‐ CRP and CDAI (linear weighted κ baseline – 0.545), DAS ‐28 CRP and SDAI (linear weighted κ – 0.689) at baseline. There was moderate agreement between DAS ‐28‐ CRP and CDAI (linear weighted κ final visit – 0.458) at final visit. There was moderate correlation between SDAI and DAS ‐28‐ CRP at final visit (linear weighted κ – 0.470). However, correlation between CDAI versus SDAI remained excellent at baseline and final visit. Patients in remission as per DAS ‐28‐ CRP had significantly more residual disease activity compared to SDAI and CDAI remission criteria. Conclusion The study shows an excellent strong positive correlation between DAS ‐28‐ CRP , CDAI and SDAI at initial evaluation but not at final visit. SDAI ‐ and CDAI ‐based remission criteria seem to be better than DAS ‐28‐ CRP ‐based remission criteria.