The QUANTA Flash(®) CTD Screen Plus is a chemiluminescent immunoassay (CIA) for the detection of the major antinuclear antibodies (ANA) on the BIO-FLASH(®) platform. NOVA View(®) is an automated fluorescence microscope that acquires digital images of indirect immunofluorescent assay (IFA) slides. Our goal was to evaluate the clinical performance of the two automated systems and compare their performance to that of traditional IFA. Sera from patients with systemic autoimmune rheumatic diseases (SARD, n = 178), along with disease and healthy controls (n = 204), were tested with the CTD CIA and with NOVA Lite(®) HEp-2 ANA, using both the manual method of reading the IFA slides and the NOVA View instrument. The CTD CIA showed 78.1% sensitivity for SARD, coupled with 94.1% specificity. Manual IFA and NOVA View showed somewhat higher sensitivity (81.5 and 84.8% in SARD, respectively), but significantly lower specificity (79.4 and 64.7%, respectively). Both automated systems displayed somewhat different performance, due to the different principals of ANA detection: IFA with NOVA View digital image interpretation had higher sensitivity, while the CTD CIA showed higher specificity. With the added benefits of full automation, the new CTD CIA is an attractive alternative to traditional ANA screening.

The American College of Rheumatology position statement on ANA testing stipulates the use of IIF as the gold standard method for ANA screening 1 . Although IIF is an excellent screening test in expert hands, the technical difficulties of processing and reading IIF slides -such as the labor intensive slide processing, manual reading, the need for experienced, trained technologists and the use of dark room -make the IIF method difficult to fit in the workflow of modern, automated laboratories.The first and crucial step towards high quality ANA screening is careful slide processing. This procedure is labor intensive, and requires full understanding of the process, as well as attention to details and experience.Slide reading is performed by fluorescent microscopy in dark rooms, and is done by trained technologists who are familiar with the various patterns, in the context of cell cycle and the morphology of interphase and dividing cells. Provided that IIF is the first line screening tool for SARD, understanding the steps to correctly perform this technique is critical.Recently, digital imaging systems have been developed for the automated reading of IIF slides. These systems, such as the NOVA View Automated Fluorescent Microscope, are designed to streamline the routine IIF workflow. NOVA View acquires and stores high resolution digital images of the wells, thereby separating image acquisition from interpretation; images are viewed an interpreted on high resolution computer monitors. It stores images for future reference and supports the operator's interpretation by providing fluorescent light intensity data on the images. It also preliminarily categorizes results as positive or negative, and provides pattern recognition for positive samples. In summary, it eliminates the need for darkroom, and automates and streamlines the IIF reading/interpretation workflow. Most importantly, it increases consistency between readers and readings. Moreover, with the use of barcoded slides, transcription errors are eliminated by providing sample traceability and positive patient identification. This results in increased patient data integrity and safety.

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Background NOVA View® is a new, automated digital image analysis system, which can be used for reading and interpreting anti-nuclear antibody (ANA) testing on HEp-2 cells, based on measured Light Intensity Units (LIU) and pattern recognition. Objectives Our goal was to evaluate the analytical performance characteristics of the NOVA View®, with special attention given to precision, reproducibility and accuracy. Methods Analytical sensitivity of the system was assessed by establishing the Limit of Blank (LoB) and Limit of Detection (LoD). Precision was evaluated on four specimens ranging from negative to 3+ positive, by running them in triplicates in 5 to 10 consecutive runs. Inter-instrument agreement was assessed by processing 11 specimens in various dilutions (n=38) and 9 controls on HEp-2 slides, and scanning them with two different instruments. Positive/negative cut-off was established on 200 random normal control samples based on percentile ranking and agreement with digital image reading. Endpoint titers as assessed from a single well by the NOVA View software were compared to results obtained from dilution series on the same specimens (n=20). Results Samples are run on NOVA Lite® barcoded slides, providing positive patient identification from processing through interpretation. NOVA View results are expressed in LIU, and interpreted as negative or positive based on a pre-set cut-off. The detection limit of the system was established at 49 LIU, while the positive/negative cut-off at 66 LIU. The within-run and between-run coefficients of variation (CV%) of the strong positive specimen were 9.2 and 10.2%. The two week positive (around the cut-off) specimens produced 14.3% and 24.8% within-run CV%, and 21.1% and 27.0% between-run CV%. The negative specimen was consistently negative in all 30 replicates. Comparison of LIU values obtained on two different instruments showed tight correlation (R2=0.975) and only 4.1 LIU estimated bias (difference) at the cut-off level. Endpoint titers as assessed from a single well by the NOVA View matched with those obtained by testing dilution series in 9 samples, and were within ± one step in 9 specimens. In two specimens with nucleolar and homogenous patterns, respectively, the NOVA View endpoint titer differed from the manual titer with two dilution steps. Conclusions Indirect immunofluorescence (IIF) testing on HEp-2 cells is considered the reference method for ANA detection.Lack of standardization of the manual method, however, still remains a concern.The NOVA View opens a new chapter of objective, precise, reproducible and quantifiable ANA detection, which could produce comparable results between laboratories. The stored digital images can be viewed and shared at any time, thereby promoting training and patient follow-up. Disclosure of Interest G. Lakos Employee of: Inova Diagnostics, Inc., C. Buchner Employee of: Inova Diagnostics, Inc., C. Bryant Employee of: Inova Diagnostics, Inc., R. Rosenblum Employee of: Inova Diagnostics, Inc., P. Baker Employee of: Inova Diagn...