Comparison of rheumatoid arthritis composite disease activity indices and residual activity in a Brazilian multicenter study- REAL study.

INTRODUCTION: Rheumatoid arthritis (RA) composite disease activity indices have become handy tools in daily clinical practice and crucial in defining remission or low disease activity, the main target of the RA treatment. However, there is no definition of the best index to assess disease activity in clinical practice. OBJECTIVES: To compare the residual activity among the indices with the ACR/EULAR remission criteria (Boolean method) to identify the most feasible for assessing remission in daily practice, also considering correlation and concordance, sensibility, and specificity. PATIENTS AND METHODS: We selected 1116 patients with established RA from the real-life rheumatoid arthritis study database-REAL. The composite disease activity indices-DAS28-ESR, DAS28-CRP, SDAI, and CDAI-and their components were compared to the Boolean method to identify residual activity using binomial regression. The indices were analyzed for correlation and agreement using the Spearman index and weighted kappa. The chi-square test evaluated sensibility and specificity for remission based on the Boolean method. RESULTS: DAS28-CRP overestimated remission and confirmed higher residual activity than SDAI and CDAI. The indices showed good correlation and agreement, with a better relationship between SDAI and CDAI (k:0,88). CDAI and SDAI showed higher sensitivity and specificity for remission based on the Boolean method. CDAI was performed in 99% of patients, while DAS28 and SDAI were completed in approximately 85%. CONCLUSIONS: Although all composite indices of activity can be used in clinical practice and showed good agreement, CDAI and SDAI have better performance in evaluating remission based on the Boolean method, showing less residual activity and higher sensibility and specificity. In addition, CDAI seems to be more feasible for disease activity evaluation in daily clinical practice, especially in developing countries.

Performance of the Rheumatoid Arthritis Disease Activity Index in the Assessment of Disease Activity in Rheumatoid Arthritis-Findings From the REAL Study.

BACKGROUND/OBJECTIVE: Although telemedicine use has been under discussion for decades, this topic has gained unprecedented importance during the COVID-19 pandemic. The Rheumatoid Arthritis Disease Activity Index (RADAI) is a user-friendly tool, fully self-administered, to assess rheumatoid arthritis (RA) disease activity. The aim of this study was to compare the performance of RADAI with other disease activity indices, functional status, and inflammatory markers in a large cohort of RA patients. METHODS: We assessed the concurrent validity of RADAI against Clinical Disease Activity Index (CDAI), Disease Activity Score in 28 Joints-C-reactive protein, Disease Activity Score in 28 Joints-erythrocyte sedimentation rate, Simplified Disease Activity Index, and physician assessment of disease activity and the correlation of RADAI with Health Assessment Questionnaire-Disability Index and inflammatory markers at the REAL Study baseline. We also evaluated the correlation of the change in RADAI and the change in CDAI over a 6-month follow-up. RESULTS: From the 1115 patients included in the REAL Study, 1113 had RADAI scores in the first assessment. At baseline, correlations between RADAI and other disease activity indices were strong, ranging from 0.64 (comparison with physician assessment) to 0.79 (comparison with CDAI). Correlation between the change in RADAI score over the 6 months of follow-up and the change in CDAI score over the same period was moderate/strong for the overall group and within the stratified analyses. CONCLUSION: The strong correlation of RADAI with other well-established tools for disease activity measurement reassures its use with RA patients' follow-up, especially in this new era of telemedicine.