Comparison among different indicators of disease activity in patients with rheumatoid arthritis

Abstract

Objective To compare disease activity score 28 joints DAS28, simplified disease activity index(SDAI) and clinical disease activity index(CDAI) for assessing disease activity in patients with rheumatoid arthritis (RA). Method Total of 423 patients with RA hospiltalized in the department of the first Affiliated Hospital of Anhui Medical University between January 2006 and December 2014 were enrolled in this study.DAS28, CDAI and SDAI were used to evaluate disease activity.According to the classification criteria of RA, patients were divided into three groups: group of remission or low-disease activity, group of moderate-disease activity and high-disease activity. Results ①According to classification criteria of DAS28, the patients in the above three groups were respectivelly accounted for 4.14%(17/423), 38.2%(157/423) and 57.66%(237/423). For CDAI, the ratios were 6.86%(29/423), 29.79%(126/423) and 63.36%(268/423). For SDAI, to ratio were 5.26%(22/423), 32.78%(137/423) and 61.96%(259/423). There were good correlations among CDAI, SDAI and DAS28 (Spearman correlation=0.812, 0.796; both P<0.05), and both CDAI and SDAI had well consistency with DAS28 (Kappa=0.719, 0.740, both P<0.05). ② Correlation analyses showed that CDAI and SDAI were positively correlated with DAS28(r=0.913, 0.912, both P<0.05), and there was a higher positive linear correlation between CDAI and SDAI(r=0.973, P<0.05). ③There was significant difference regarding swollen joint count, tender joint count, healthy assessment questionnaive(HAQ) score, blood platelet count, erythrocyte sedimentation Rate(ESR), C-reaction protein(CRP), rheumatoid factor(RF) among patients with different disease activity(P<0.05). All of the above indexes increased along with the rising disease activity.Serum hemoglobin(HB) levels(P<0.05) decreased along with the rising disease activity.④DAS28, CDAI and SDAI positively correlated with swollen joint count, tender joint count, HAQ score, blood platelet count, ESR, CRP and RF(P<0.05). DAS28, CDAI and SDAI negatively correlated with HB levels(P<0.05). Conclusion CDAI, SDAI and DAS28 have good association and consistency.SDAI and CDAI have better correlations with disease activity in RA. Key words: Rheumatoid arthritis; Disease activity index; Disease activity score 28 joint; Clinical disease activity idex; Simplified disease activity index