The SDAI and CDAI based remission criteria were found to be better than DAS-28-CRP-based remission criteria for RA patients. The study was aimed to compare the performance of:
1) Disease Assessment Score of 28 joints - C-reactive protein (DAS-28-CRP) 
2) Clinical Disease Activity Index (CDAI)
3) Simplified Disease Activity Index (SDAI) composite measures. 

This was done to find out the status of rheumatoid arthritis (RA) patients on methotrexate, versus DAS-28 CRP as the gold standard.

In this prospective study 135 patients having RA as per the 2010 American College of Rheumatology/European League Against Rheumatism criteria were included. The analysis of disease activity was done at baseline and every 6 weeks for 24 weeks through DAS-28-CRP, CDAI and SDAI. The study population was divided into groups of remission, low, moderate and high activity, based on 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.

The findings showed an excellent and 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. A moderate agreement was observed at the final visit, between DAS-28-CRP and CDAI (linear weighted κ final visit - 0.458). A moderate correlation was seen between SDAI and DAS-28-CRP at final visit (linear weighted κ - 0.470). The correlation between CDAI versus SDAI was excellent both at baseline and final visit. According to DAS-28-CRP, patients who are in remission had significantly more residual disease activity in comparison to SDAI and CDAI remission criteria.

Therefore study determined the appearance of an excellent and strong positive correlation between DAS-28-CRP, CDAI and SDAI at initial evaluation which was not seen at final visit. It was observed that SDAI- and CDAI-based remission criteria were better than DAS-28-CRP-based remission criteria.