Two tests to detect anti-double stranded DNA antibodies in the diagnostic value of systemic lupus erythematosus / 中华检验医学杂志

ABSTRACT

Objective To investigate the concurrent application value of indirect immunofluorescence (IIF) and enzyme-linked immunosorbent assay (ELISA) in systemic lupus erythematosus (SLE).Methods A retrospective study.All patients who took anti-double stranded DNA (dsDNA) antibody test from June 1 2011 to September 30 2011 in our department were recruited in this study.The patients' anti-dsDNA antibody results and clinical diagnosis were collected and analyzed retrospectively.The consistence,sensitivity and specificity of IIF and ELISA tests were calculated and the consistence was compared by Kappa test.Results The positive rates of detecting anti-dsDNA antibodies by ELISA and IIF tests were 16.3％ and 13.1％ respectively.The consistency between these two tests was 90.8％,and showed good correlation by Kappa test (Kappa =0.641,P ＜ 0.05 ).Of 9.2％ of inconsistent results between IIF andi ELISA,most cases ( 6.2％ ) were ELISA positive and IIF negative.Taking the clinical diagnosis of lupus as a golden standard,the accuracy of IIF and ELISA was 84.8％ and 84.4％ respectively and the difference was no significant (x2 =0.25,P ＞ 0.05 ).The sensitivity and specificity for diagnosing lupus by IIF were 46.1％ and 99.2％,and 51.3％ and 96.7％ by ELISA.Conclusions Our results suggested that anti-dsDNA antibodies in samples should be detected by both ELISA and IIF tests simultaneously.If ELISA was used first and the positive samples were further tested by IIF,at least 3％ of ELISA negative and IIF positive samples would be misdiagnosed as anti-dsDNA antibodies negative.IIF negative and ELISA positive samples should be further analyzed the affinity of anti-dsDNA antibodies in order to help the diagnosis and evaluation of SLE.