OBJECTIVE: Antidouble-stranded DNA (dsDNA) is estimated commercially by different assays in the clinical laboratory, but the lack of analytical agreement among different methods leads to difficulty in clinical interpretation. This study aims to address the clinical impact of measuring anti-dsDNA antibodies by two different assays in an Systemic Lupus Erythematosus(SLE)-based cohort. MATERIALS AND METHODS: SLE patients with test requisition simultaneously raised for anti-dsDNA by Crithidia luciliae based on indirect immunofluorescence test (CLIFT), ANA profile by line immunoassay, and ANA screening (HEp-2) were identified. Descriptive analysis, analysis of concordance or discordance between the three different assays, and multiple correspondence analysis were applied to look for hierarchical clustering association of multiple antibodies. The association between dsDNA positivity, ANA screening, ANA cluster membership, and renal status was looked into. RESULTS: Among the 70 SLE patients, all dsDNA-positive cases by CLIFT were also tested positive for ANA screening by HEp-2 (indirect immunofluorescence test). In contrast, among dsDNA-negative cases, 65.9% were ANA positive. dsDNA positivity revealed a homogenous ANA immunofluorescence pattern, whereas dsDNA-negative patients showed a predominance of mixed pattern (nuclear speckled with positive metaphases, AC30). There was a strong and statistically significant association between dsDNA positivity and ANA profile reactivity. Proteinuria was most frequently noted among the dsDNA-positive patients. Clustering of patients into three groups based on antibody profile revealed three distinct serological phenotypes. CONCLUSION: Our data demonstrates discordance between CLIFT and line immunoassay for anti-dsDNA, mainly with samples exhibiting dsDNA negativity by CLIFT but ANA screening and ANA profile positivity. With the significant discordance of results between the anti-dsDNA assays, the combined diagnostic utility of the three assays may be considered.
Raj et al. (Thu,) studied this question.