Study of role of serum amyloid A (SAA) as a marker of disease activity in juvenile idiopathic arthritis.

Abstract

Role of serum amyloid A (SAA) protein as a biomarker for the disease activity in juvenile idiopathic arthritis (JIA) has not been explored. This study was done to find its role as marker of disease activity in JIA. A case-control study with 50 newly diagnosed cases of JIA of all subtypes and 40 healthy controls was done. Serum amyloid A (SAA), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) were measured in both patients and healthy controls. Quantitative measurement of SAA level was measured by using standard human SAA enzyme-linked immunosorbent assay (ELISA). Disease activity was assessed clinically and by ultrasonography (USG) score determined by examining eight large joints (bilateral elbow, wrist, knee, ankle). Serum SAA levels were found significantly higher in JIA patients as compared with healthy controls (<i>P</i> < 0.001). Significant positive correlations were found between SAA with presence of active joints (<i>r</i> = 0.64, <i>P</i> < 0.001), ESR (<i>r</i> = 0.39, <i>P</i> < 0.05), and CRP (<i>r</i> = 0.36, <i>P</i> < 0.05). However, significant correlations was not found between ESR and the presence of active joints (<i>r</i> = 0.21, <i>P</i> = 0.225) and between CRP and the presence of active joints (<i>r</i> = 0.034, <i>P</i> = 0.855). The mean USG score of patients with increased SAA level was significantly higher than that of patients with normal SAA level (<i>P</i> < 0.05). A significant increase in SAA levels was found in JIA patients with strong positive correlation between SAA level and JIA disease activity. The study discerned SAA to be a more sensitive laboratory marker than ESR and CRP for evaluating the presence of active joints.