Disease activity measurement in rheumatoid arthritis: comparison of 3 disease activity index tools at Kenyatta National Hospital

Abstract

Objectives: To compare the congruence of the Disease Activity Score with 28-joint count (DAS-28) with the Simplified Disease Activity Index (SDAI) and the Clinical Disease Activity Index (CDAI) in measuring disease activity in Rheumatoid Arthritis (RA) patients at the Kenyatta National Hospital (KNH). Design: Cross-sectional descriptive study. Setting: Rheumatology Out-Patient Clinic (ROPC) at KNH. Subjects: One hundred and four patients who fulfilled the 2012 American College of Rheumatology Classification Criteria for RA. Results: DAS28, SDAI and CDAI were significantly correlated with each other on a group level (p < 0.001). Internal consistency was highest for CDAI (alpha = 0.705) and lowest for DAS28 (alpha = 0.67). Kappa statistics revealed substantial degree of agreement with respect to controlled, active, moderate and high disease activity categories according to the three scores. Conclusion: Both SDAI and CDAI proved to be in congruence with DAS28 in daily clinical routine. SDAI and CDAI were found to be more stringent in defining remission.