DAS28-ESR and DAS28-CRP - are they Interchangeable in Measuring the Activity of Rheumatoid Arthritis in Response to Treatment with Biological Agents?

INTRODUCTION: The European League Against Rheumatism updates the recommendations for managing rheumatoid arthritis. Again, it is not specified which DAS28 is there in view (with erythrocyte sedimentation rate or C-reactive protein). AIM: The aim of the study is to check whether Disease Activity Score-28 (erythrocyte sedimentation rate) and Disease Activity Score-28 (C-reactive protein) represent equally the activity of rheumatoid arthritis in the course of treatment with biological agents. MATERIALS AND METHODS: In a retrospective study we analyzed the database of real clinical practice over a 12-month period of biological treatment of rheumatoid arthritis. Disease Activity Score-28 (erythrocyte sedimentation rate) and (C-reactive protein) are compared at the start and at the end of the study. RESULTS: The mean difference between the two variants of disease activity scores at baseline and at the end of the study is significant (p < 0.001). The Disease Activity Score-28 (erythrocyte sedimentation rate) represents a remarkably small proportion of patients with remission and low activity (<3.2) at baseline (18.46%) and at the end of the study (40.51%). Disease Activity Score-28 (C-reactive protein) represents a significantly high proportion of patients in remission and low activity (<3.2) at the end of the study (69.74%). Estimates of activity according to the two variants show significant discrepancy between each other and low level of agreement (kappa = 0.235-0.464). Discrepancies are not related to the type of biological drug (anti-TNF or not). CONCLUSION: The two DAS28 variants are not interchangeable with the same threshold for low activity in measuring the response to biological therapy.