Diagnostic Validation of Fully Automated ANA Detection by Indirect Immunofluorescence: An Initiative towards Standardization

Abstract

Objective: This study entailed the diagnostic validation of an automated system utilized for the detection of antinuclear antibodies (ANA) through the indirect immunofluorescence method, juxtaposed with the traditional manual approach for ANA detection. The study was undertaken in the Department of Chemical Pathology at Chughtai Laboratory, Lahore, spanning a period of three months, from December 2018 to February 2019. Methods: A total of 132 patient samples were gathered for the purpose of conducting this validation study. The manual detection of ANA was performed by using slides coated with HEp-2 cells. An LED fluorescence microscope was used for the interpretation of results by a trained technologist as well as by a pathologist. After manual detection of ANA, the same specimens were evaluated by a fully automated ANA-IIF detection system which has inbuilt characteristics of slide processing, microscopy, image capturing and displaying specific ANA patterns. The results were interpreted as positive for those samples having sample titers more than 1:80. The same criteria of positivity were used for both manual and automatic systems. Results: A total of 132 specimens underwent evaluation through both manual and automated ANA indirect immunofluorescence (IIF) detection systems. The concordance between these two methodologies exhibited an overall agreement of 95.7%, with a positive agreement of 97.5% and a negative agreement of 94.9%. Cohen's kappa value stood at 91.7% (ranging from 83.4% to 98.9%), indicating a robust correlation between the two detection systems. The diagnostic sensitivity of the fully automated IIF methodology demonstrated 89.38% (with a 95% confidence interval of 77.24% to 96.13%) and the diagnostic specificity of 95.22% (with a 95% confidence interval of 87.88% to 98.76%). Conclusion: The fully automated showed strong correlation with manual ANA detection methodology based on the principle of indirect immunofluorescence.