How much does Disease Activity Score in 28 joints ESR and CRP calculations underestimate disease activity compared with the Simplified Disease Activity Index?

Objectives Disease Activity Score in 28 joints calculated with C-reactive protein (DAS28-CRP) is used instead of erythrocyte sedimentation rate (DAS28-ESR) to assess rheumatoid arthritis disease activity; however, values for remission and low disease activity (LDA) for DAS28-CRP have not been validated. American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) guidelines suggest remission should be calculated by Simplified Disease Activity Index (SDAI) rather than DAS28-ESR. We examined values of remission and LDA of DAS28-CRP that correspond to the respective cut-off points for DAS28-ESR and SDAI from five clinical trials. Methods DAS28-CRP cut-offs that best correspond to DAS28-ESR remission