Abstract
Indirect immunofluorescence assay (IFA) using HEp-2 cells as a substrate is the gold standard for detecting antinuclear antibodies (ANA) in patient serum. However, the ANA IFA has labor-intensive nature of the procedure and lacks adequate standardization. To overcome these drawbacks, the automation has been developed and implemented to the clinical laboratory. The purposes of this study were to evaluate the analytical performance of a fully automated Helios ANA IFA analyzer in a real-life laboratory setting, and to compare the time and the cost of ANA IFA testing before and after adopting the Helios system. A total of 3,276 consecutive serum samples were analyzed for ANA using the Helios system from May to August 2019. The positive/negative results, staining patterns, and endpoint titers were compared between Helios and visual readings. Furthermore, the turnaround time and the number of wells used were compared before and after the introduction of Helios system. Of the 3,276 samples tested, 748 were positive and 2,528 were negative based on visual readings. Using visual reading as the reference standard, the overall relative sensitivity, relative specificity, and concordance of Helios reading were 73.3, 99.4, and 93.4% (κ = 0.80), respectively. For pattern recognition, the overall agreement was 70.1% (298/425) for single patterns, and 72.4% (89/123) for mixed patterns. For titration, there was an agreement of 75.9% (211/278) between automated and classical endpoint titers by regarding within ± one titer difference as acceptable. Helios significantly shortened the median turnaround time from 100.6 to 55.7 h (P < 0.0001). Furthermore, routine use of the system reduced the average number of wells used per test from 4 to 1.5. Helios shows good agreement in distinguishing between positive and negative results. However, it still has limitations in positive/negative discrimination, pattern recognition, and endpoint titer prediction, requiring additional validation of results by human observers. Helios provides significant advantages in routine laboratory ANA IFA work in terms of labor, time, and cost savings. We hope that upgrading and developing softwares with more reliable capabilities will allow automated ANA IFA analyzers to be fully integrated into the routine operations of the clinical laboratory.
Highlights
Antinuclear antibodies (ANA) are one of the most important serological markers used for the diagnosis of systemic autoimmune rheumatic diseases (SARD) such as systemic lupus erythematosus (SLE), systemic sclerosis (SSc), Sjögren’s syndrome (SjS), mixed connective tissue disease (MCTD), and idiopathic inflammatory myopathy (IIM)
To the best of our knowledge, this is the most extensive single-center investigation assessing the performance, titration capability, turnaround times (TATs), and cost-effectiveness of Helios, a fully automated analyzer used for daily ANA immunofluorescence assay (IFA) testing in a large set of consecutive patients with suspected SARD in a real-life setting
The overall relative sensitivity, relative specificity, and concordance of Helios reading was 73.3, 99.4, and 93.4% (k = 0.80), respectively, which varied considerably from values obtained in several previous studies using various automated analyzers [23,24,25,26]
Summary
Antinuclear antibodies (ANA) are one of the most important serological markers used for the diagnosis of systemic autoimmune rheumatic diseases (SARD) such as systemic lupus erythematosus (SLE), systemic sclerosis (SSc), Sjögren’s syndrome (SjS), mixed connective tissue disease (MCTD), and idiopathic inflammatory myopathy (IIM). Steady increases in the prevalence of SARD have been reported in recent years, which has been attributed to a variety of causes, including exposure to environmental chemicals and toxins, an aging population and its associated chronic diseases, and use of particular drug regimens [1] With this increase in disease prevalence, the ANA test requests are increased by non-rheumatological clinicians to exclude SARD in patients due to the high negative predictive value of ANA measurement [2, 3]. In addition to such increased demand for ANA testing and standardization efforts, the automation of slide preparation, image acquisition, titration, and interpretation were developed and evaluated for implementation to the clinical laboratory [8, 19,20,21,22,23,24,25,26,27,28,29]
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