Is CDAI comparable to DAS 28 and SDAI regarding inter-observer agreement and correlation to MHAQ in Egyptian RA patients?

Choosing between the different disease activity indices used for rheumatoid arthritis RA evaluation in clinical practice and research is often difficult. The aim of the current study was to compare clinical disease activity index (CDAI) to simplified disease activity index (SDAI), and disease activity score 28 (DAS28) regarding inter-observer reliability and correlation to the modified health assessment questionnaire (MHAQ) in a cohort of Egyptian RA patients. This study included one hundred RA patients. Every patient had an independent clinical evaluation made by two rheumatologists (professor and candidate) to evaluate disease activity using DAS28 with its 4 types, CDAI and SDAI. We used Cohen's weighted kappa coefficient to measure the inter-observer agreement between the professor and candidate in different disease activity measures. Correlation between MHAQ and disease activity measures was made with Spearman's rho test. Inter-observer agreement in CDAI and DAS28 values was almost perfect. A strong positive correlation was found between professor and candidate regarding the tested activity indices (p<0.001), and a positive correlation was found between MHAQ and all Disease Activity Scores made by both professor and candidate (p<0.001). CDAI proved to be comparable to other disease activity scores regarding inter-observer agreement and relation to MHAQ.