The evaluation of dot immunogold filtration method in detection of serum SAA and its clinical value of diagnosing the infectious diseases of children

Abstract

Objective The purpose of this study was to assess the analysis capabilities of the dot immunogold filtration method on detecting serum amyloid A (SAA) protein in blood.It also aimed to research the clinical value of SAA in diagnosing the infectious diseases of children. Methods (1) The performance evaluation including the accuracy, within-run precision, inter assay variations, the linear and the distraction-analysis of SAA-SPOT was estimated following the EP file; From March to July in 2014, children from five 3A Grade hospitals in Guangdong Province were enrolled into this observational study.Data including white blood WBC count, CRP and SAA were obtained.(2) From March to July in 2014, children from five 3A Grade hospitals in Guangdong Province were enrolled randomly into this observational study.This study used a cross-sectional survey research method, and 386 children with bacterial infection and 219 children with virus infection were as the research object.The general, clinical diagnosis, treatment information as well as the data of blood SAA, C-reactive protein (CRP) and white blood cell (WBC) of children were collected.Data were analyzed by variance, independent t test, ROC curve analysis and stepwise regression statistics method. Results (1) The average recovery rate is 103.74 %.Coefficient of variation (CV) for 10 mg/L,100 mg/L within-run assays were 8.77%, 3.61% and between-run assays were 9.01%, 3.74%; the inter-day CV were 9.07%, 4.03% respectively; the linear range was 5 mg/L-200 mg/L, hemoglobin(5 g/L)，serum bilirubin(800 μmol/L)，triglyceride(TG, 22 mmol/L), and had no interference in SAA detection.When compared to the BNPRO quantitate system of SIEMENS, the coefficient of association of detection of SAA by SAA-SPOT was R2=0.96.(2) Compared with control group, the serum SAA of infection group (bacterial infection group,t=13.05，P=0.001；virus infection group t=7.68, P=0.001) and SAA/CRP ratio (bacterial infection group t=2.29, P=0.023; virus infection group t=3.32, P=0.01) were significantly increased.(3) The serum CRP and SAA rose similarly in bacterial infection, while in viral infection, only SAA increased significantly, CRP had no apparent change.In combination with CRP and WBC, SAA had the better diagnostic efficiency apparently. Conclusions As a POCT detection project, analysis capabilities of the SAA assayed by domestic SAA-SPOT can meet the requirements of clinical test.Combined with CRP, WBC and SAA can improve the efficiency in the diagnosing of infectious disease especially in the virus infection.As a new biomarker of infections, SAA is useful for the early auxiliary diagnosis and differential diagnosis of childhood infection. （Chin J Lab Med，2014,37：836-841） Key words: Infection; Serum amyloid A protein; C-Reactive protein; Gold colloid; Reagent kits, diagnostic