Comparative diagnostic performance of different rapid antigen detection tests for COVID-19 in the real-world hospital setting

Bruzzone, Bianca; De Pace, Vanessa; Caligiuri, Patrizia; Ricucci, Valentina; Guarona, Giulia; Pennati, Beatrice M.; Boccotti, Simona; Orsi, Andrea; Domnich, Alexander; Da Rin, Giorgio; Icardi, Giancarlo

Background The availability of accurate and rapid diagnostic tools for COVID-19 is essential for tackling the ongoing pandemic. The aim of this study was to quantify the performance of different available types of antigen-detecting rapid diagnostic tests (Ag-RDTs) in the real-world hospital setting. Methods In this retrospective analysis the diagnostic performance of seven different Ag-RDTs was compared with the real-time reverse transcription quantitative polymerase chain reaction (RT-qPCR) in terms of sensitivity, specificity and expected predictive values. Results A total of 321 matched Ag-RDT–RT-qPCR samples were analyzed retrospectively. The overall sensitivity and specificity of Ag-RDTs were 78.7% and 100%, respectively. However, a wide range of sensitivity estimates by brand (66.0–93.8%) and cycle threshold (Ct) cut-off values (Ct <25: 96.2%; Ct 30–35: 31.1%) was observed. The optimal Ct cut-off value that maximized sensitivity was 29. Conclusions The routine use of Ag-RDTs may be convenient in moderate-to-high intensity settings when high volumes of specimens are tested every day. However, diagnostic performance of the commercially available tests may differ substantially.