Clinical comparison of QUANTA Flash dsDNA chemiluminescent immunoassay with four current assays for the detection of anti-dsDNA autoantibodies.

INTRODUCTION: The objective of the present study was to compare QUANTA Flash dsDNA, a chemiluminescent immunoassay (CIA) on the BIO-FLASH, a rapid-response chemiluminescent analyzer, to three other anti-dsDNA antibody assays and to Crithidia luciliae indirect immunofluorescence test (CLIFT). METHODS: In the first part of the study, 161 samples, 61 from patients suffering from systemic lupus erythematosus (SLE) and 100 from a disease control group, were tested by QUANTA Flash dsDNA CIA, QUANTA Lite dsDNA SC ELISA, BioPlex 2200 multiplex flow immunoassay (MFI), ImmuLisa dsDNA ELISA, and NOVA Lite CLIFT. A second cohort of 69 SLE patients was then tested by QUANTA Flash dsDNA and CLIFT to expand the study. RESULTS: The overall qualitative agreements varied between 77.0% (NOVA Lite CLIFT versus QUANTA Lite) and 89.4% (ImmuLisa versus NOVA Lite CLIFT). The clinical sensitivities for the anti-dsDNA antibody tests varied from 8.2% (NOVA Lite CLIFT) to 54.1% (QUANTA Lite), while the clinical specificities varied from 88.0% (BioPlex 2200) to 100.0% (NOVA Lite CLIFT). Good correlation was found between QUANTA Flash dsDNA and NOVA Lite CLIFT. CONCLUSION: Significant variations among dsDNA methods were observed. QUANTA Flash dsDNA provides a good combination of sensitivity and specificity for the diagnosis of SLE and good agreement to CLIFT.

Analytical and clinical comparison of two fully automated immunoassay systems for the diagnosis of celiac disease.

OBJECTIVE: Here we compared analytical and clinical performance characteristics of two novel automated assay systems for the detection of celiac disease (CD) specific antibodies: QUANTA Flash (INOVA Diagnostics, Inc.) and EliA (Thermo Scientific). METHODS: A total of 74 biopsy-proven CD patients (2 with IgA deficiency) and 138 controls were tested by both methods. RESULTS: Sensitivities of QUANTA Flash assays ranged from 35.1% to 90.5% and specificities from 96.4% to 99.3%, while sensitivities for EliA assays ranged from 37.8% to 90.5% (equivocal considered positive) and specificities from 97.1% to 100.0%. Good qualitative agreement was found between all assays. Thirty-four (50.0%) of the 68 QUANTA Flash h-tTG IgA positive results were higher than 10 times the upper limit of normal (ULN). In contrast, only 22.8% of the EliA tTG IgA positive samples were >10x ULN. Seventy-three (98.6%) biopsy-proven CD patients were correctly identified with the QUANTA Flash h-tTG IgA+DGP IgG combination, while 64 (86.5%) and 72 (97.3%) (depending on equivocal range) were identified with the same combination of EliA assays. CONCLUSION: The QUANTA Flash CD assays have outstanding clinical performance. Of particular clinical significance, in light of proposals to decrease the absolute necessity of biopsy, was the demonstration that 50% of the QUANTA Flash h-tTG IgA results were >10x ULN.

Multiplex assays to diagnose celiac disease.

Patients with celiac disease are sensitive to the gluten fractions of wheat. Symptoms include gastrointestinal problems and a failure to thrive in children, but may range from headaches to general malaise in adults. Thus, it is difficult to diagnose celiac disease by symptoms alone. The standard diagnostic criteria include the presence of the characteristic anti-gliadin or anti-tissue transglutaminase antibodies (anti-tTG) in serum, flattened mucosa on intestinal biopsy, and improved symptoms on a gluten-free diet. Because of the ease of use of the tTG enzyme-linked immunosorbent assay (ELISA) compared to endomysial by indirect immunofluorescence assay, there has been much more screening for celiac disease in recent years. This increased screening showed that celiac disease was more prevalent than previously believed. We compared a new multiplex assay that includes a novel form of deamidated gliadin and recombinant human tTG as the antigens to other assays using standard antigens. In addition, the new assay detects the presence of selective IgA deficiency, which shows a 10-fold increase in prevalence in patients with celiac disease compared to the general population. The combination of sensitivity and specificity of the new multiplex assay was equal or better than those for standard assays. Thus the performance, ease of use, and ability to measure three clinically important parameters in a single test make the new multiplex assay a viable alternative to standard assays in a clinical lab.