Evaluation of the Diagnostic Performance of SARS-CoV-2 Rapid Antigen Tests in COVID-19 Patients

The gold standard in the definitive diagnosis of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is nucleic acid amplification tests (NAAT) due to their high sensitivity and specificity in de-tecting viral ribonucleic acid. However, while leaving two years behind in the pandemic, resources have come to the point of exhaustion in terms of both the economy and the manpower working in the field of health services. Therefore, the need for rapid, simple and accurate tests to diagnose SARS-CoV-2 infection continues. In this study, it was aimed to compare the performance characteristics of SARS-CoV-2 rapid antigen tests (RAgT) in the diagnosis of coronavirus disease 2019 (COVID-19) cases with the real-time reverse transcription-polymerase chain reaction (rRT-PCR) method. In Istanbul University-Cerrahpaa Fa-culty of Medicine COVID-19 Molecular Diagnosis Laboratory, SARS-CoV-2 RNA positive respiratory tract samples with viral loads of < 25 Ct (cycle of treshold), 25-29 Ct, 30-35 Ct and 35< Ct, a total of 205 patient samples were selected in four groups. SARS-CoV-2 positive samples were studied by lateral flow method (LFA) using twelve commercial RAgTs of different companies and their performances were evalu-ated. In addition, 90 samples were selected from various respiratory tract samples archived, which were sent to our laboratory for the identification of the non-COVID-19 pathogen(s) causing the respiratory tract infection between 2020-2022 and their specificities for RAgTs were evaluated to avoid cross reacti-vity. The sensitivities of the SARS-CoV-2 RAgTs included in the study, ranged from 40.4-97.5%, while the sensitivity of most of the kits (8/12), at 25 Ct values, was _ 90%, which is the minimum limit in the European Centre for Disease Prevention and Control (ECDC)'s guideline for the use of SARS-CoV-2 RAgTs. The specificities of RAgTs were found to be between 90-100%. When the concordance of SARS-CoV-2 RAgTs with rRT-PCR positivity was evaluated with the kappa coefficient, the concordance of only one RAgT was found to be statistically significant (Kappa= 0.88). SARS-CoV-2 RAgTs have a potential use as a diagnostic tool in symptomatic people, as a routine screening tool in community living environments, and in situations such as ending the isolation of the patients. Each country should carry out validation studies before the use of these tests, taking into account of their socio-economic situation, healthcare infrastructure and current epidemiological data of COVID-19.