Comparison of quantitative and qualitative anti-dsDNA assays

Objective: In evaluation of systemic lupus erythematosus (SLE), anti-double-stranded DNA antibodies (anti-dsDNA) play a significant role in diagnosis, monitoring SLE activity, and assessing prognosis. However, evaluations of the performance and limitations for recently developed methods for anti-dsDNA assessment are sparse. Methods: Specimens used for antinuclear antibody testing (n = 129) were evaluated for anti-dsDNA assay comparability across 4 medical centers in the United States. The methods compared were Werfen Quanta Lite dsDNA, Zeus Scientific dsDNA Enzyme Immunoassay, Bio-Rad multiplex immunoassay (MIA) dsDNA, ImmunoConcepts Crithidia, and Bio-Rad Laboratories Crithidia. Results : For quantitative anti-dsDNA measurements, Spearman's correlation coefficient was highest between Zeus and Werfen (rho = 0.86; CI, 0.81-0.90; P < .0001). Comparison of MIA to Werfen or Zeus yielded similar results to each other (rho = 0.58; CI, 0.44-0.68; P < .0001; and rho = 0.59; CI, 0.46-0.69; P < .0001, respectively), but lower than the correlation between Zeus and Werfen. Positive concordance between assays ranged from 31.4% to 97.1%, and negative concordance between assays ranged from 58.5% to 100%. The detection of anti-dsDNA in those with SLE diagnosis ranged from 50.9% to 77.4% for quantitative assays and 15.1% to 24.5% for Crithidia assays. Conclusion: Current quantitative anti-dsDNA assays are not interchangeable for patient follow-up. Crithidia-based assays demonstrate high negative concordance and lack positive concordance among the methods.