key: cord-0015491-m06bta0d
authors: Marchán-López, Álvaro; García, Blanca Ayuso
title: Diagnostic performance of antigen testing for SARS-CoV-2
date: 2021-02-22
journal: J Pediatr
DOI: 10.1016/j.jpeds.2021.02.052
sha: 13bf44362c364b5d4733a6f2f51eaeabcef92d9d
doc_id: 15491
cord_uid: m06bta0d

nan

We read with interest the brief report by Villaverde et al (1) in which the authors posit a low diagnostic performance of antigen testing for SARS-CoV-2 in children. We agree that reverse transcriptase polymerase chain reaction testing (RT-PCR) is the diagnostic gold standard and that it would be desirable to perform timely RT-PCR in every suspect case, which unfortunately is not realistic. After a detailed consideration of their article, we would like to offer the following remarks.

When validating a diagnostic tool a proper definition of the gold standard is required (2) .

The authors claimed that testing targeted E and RdRp genes(1), but no description of the RT-PCR kit or kits that were used were presented, nor were the definitions of "positive RT-PCR test" specified in terms of the required number of replicated genes and the cycle threshold cutoff values. Since in a pandemic setting even a low viral load in a symptomatic patient should prompt a COVID-19 diagnosis(3), the quantitative aspect of this issue seems to be minor in contrast to the reproducibility issues.

Additionally, the study is stated to be retrospective(1), so it is unclear why (and how many) patients were asked consent for paired sampling, and when the sample size was estimated. If patients truly were enrolled retrospectively, selection criteria, and whether paired sampling was standard of care in the participating centers, should be clarified.

Simply put, a diagnostic test validation study should not have a retrospective design (2) .

Lastly, we would like to remark that 98 out of every 100 negative-testing patients in the study were not infected by SARS-CoV-2(1), which should be reassuring for clinicians in their everyday emergency department practice.

J o u r n a l P r e -p r o o f

Diagnostic Accuracy of the Panbio SARS-CoV-2 Antigen Rapid Test Compared with Rt-Pcr Testing of Nasopharyngeal Samples in the Pediatric Population

Technical Guidance Series for WHO Prequalification -Diagnostic Assessment: Principles of performance studies. Geneva: World Health Organization

To Interpret the SARS-CoV-2 Test, Consider the Cycle Threshold Value