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.