Performance comparison of four anti-dsDNA antibodies assays in Chinese systemic lupus erythematosuspatients patients / 中华风湿病学杂志

ABSTRACT

Objective To compare the performance of four commercial anti-dsDNA antibody assays,i.e,BioPlex 2200 (BioPlex),Farr radioimmunoassay (Farr),MESACUP DNA-Ⅱ TEST ds [MBL-enzyme linked immunosorbent assay (ELISA)] and Anti-dsDNA-NcX ELISA (IgG) (EURO-ELISA),Antoantibodies Profile Assay Kit (HOB-Chemiluminescent Immunoassay) in disease activity assessment of systemic lupus erythematosus (SLE).Methods SLE patients (n=119) as well as healthy controls (n=200) and disease controls (n=100) were recruited and their serum anti-dsDNA antibodies were detected by BioPlex,Farr,MBL-ELISA,EURO-ELISA,and a standard Crithidia luciliae indirect immunofluorescence test (CLIFT).The consistency between above four methods to CLIFT was analyzed.The correlation of anti-dsDNA antibody level of these four methods to SLE disease activity was assessed.All data analyses were performed with Statistical product and service solutions (SPSS) 16.0 (SPSS.Inc) and GraphPad Prism 4.0.3 (GraphPad).Unless otherwise specified,all data in this study were expressed as mean±standard deviation.Cut-off values of the anti-dsDNA quantification methods were set by the manufacturers.Chi square and kappa coefficients were adopted to assess the agreement determination and correlation analysis between anti-dsDNA level and SLE disease activity (SLEDAI).Receiver-operator characteristic (ROC) curve analysis was used to compare the specificity and sensitivity of the anti-dsDNA assays.Student's t test was adopted for the comparison of anti-dsDNA levels by different methods between SLE and SLE+LN groups.A p value small than 0.05 was considered statistically significant.Results Using cut-off values set by the manufacturers,BioPlex demonstrated the highest overall agreement with CLIFT,while MBL-ELISA and EURO-ELISA showed the highest positive agreement with CLIFT.Disease activity correlation analysis showed that SLEDAI score correlated poorly with anti-dsDNA level in Farr assay,but strongly with the other three assays.Bioplex had a better performance in terms of SLE activity index corelation (r=0.297 6,P=0.001 2).Moreover,anti-dsDNA level differed in SLE patients with renal lupus nephritis in BioPlex assay (P=0.026 8),but not in the other assays.In ROC curve analysis,BioPlex showed the largest area under the curve (AUC) over other assays.Conclusion Bio Plex assay has better sensitivity and specificity than Farr,MBL-ELISA and EURO-ELISA and correlates well with SLE disease activity.