Rapid Antigen Test LumiraDx TM vs. Real Time Polymerase Chain Reaction for the Diagnosis of SARS-CoV-2 Infection: A Retrospective Cohort Study

Anna Maria Cattelan, Lolita Sasset, Federico Zabeo, Anna Ferrari, Lucia Rossi, Maria Mazzitelli, Silvia Cocchio and Vincenzo Baldo
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Anna Maria Cattelan: Infectious and Tropical Diseases Unit, Azienda Ospedale Università di Padova, 35128 Padova, Italy
Lolita Sasset: Infectious and Tropical Diseases Unit, Azienda Ospedale Università di Padova, 35128 Padova, Italy
Federico Zabeo: Department of Cardiac Thoracic and Vascular Sciences and Public Health, University of Padova, 35127 Padova, Italy
Anna Ferrari: Infectious and Tropical Diseases Unit, Azienda Ospedale Università di Padova, 35128 Padova, Italy
Lucia Rossi: Microbiology Department, Azienda Ospedale Università di Padova, 35128 Padova, Italy
Maria Mazzitelli: Infectious and Tropical Diseases Unit, Azienda Ospedale Università di Padova, 35128 Padova, Italy
Silvia Cocchio: Department of Cardiac Thoracic and Vascular Sciences and Public Health, University of Padova, 35127 Padova, Italy
Vincenzo Baldo: Department of Cardiac Thoracic and Vascular Sciences and Public Health, University of Padova, 35127 Padova, Italy

IJERPH, 2022, vol. 19, issue 7, 1-12

Abstract: Background: Real time reverse transcription polymerase chain reaction (real time RT-PCR) testing is the gold standard for the diagnosis of SARS-CoV-2 infections. However, to expand the testing capacity, new SARS-CoV-2 rapid antigen tests (Ag-RDTs) have been implemented. Ag-RDTs are more rapid, but less reliable in terms of sensitivity, and real-life data on their performance in comparison with the real time RT-PCR test are lacking. Methods: We aimed at assessing the diagnostic performance of the third-generation antigenic swab LumiraDx™ compared with real time RT-PCR in a retrospective cohort study at the Infectious Diseases Unit of Padua. All of the patients who were consecutively tested for SARS-CoV-2 in our centre (by both real time RT-PCR and Ag-RTD LumiraDx TM ) from 19 January to 30 May 2021, were included. Cycle-threshold (Ct) values of positive real time RT-PCR were recorded as well as the number of days from symptoms’ onset to testing. Results: Among the 282 patients included, 80.9% (N = 228) tested positive to real time RT-PCR, and among these, 174 tested positive also to LumiraDx™. Compared with real time RT-PCR, which is considered as the gold standard for the assessment of the presence/absence of SARS-CoV-2 infection, LumiraDx™ showed an overall sensitivity of 76.3% and specificity of 94.4%. Sensitivity increased to 91% when testing was performed <10 days from symptoms’ onset, and to 95% when considering Ct < 25. Multivariable binomial logistic regression showed that false negative LumiraDx™ results were significantly associated with high Ct values, and with further testing from symptoms’ onset. Conclusions: The results of our study suggested that the LumiraDx™ SARS-CoV-2 antigen assay may be appropriate for the detection of SARS-CoV-2 infection, especially in its early phase when the test largely meets the performance requirements of the European Centre for Disease Prevention and Control (ECDC).

Keywords: SARS-CoV-2; COVID-19; diagnosis; rapid antigen testing; RT-PCR; agreement; sensitivity; specificity; positive predictive value; negative predictive value; accuracy (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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