Diagnostic Performance Characteristics of the Operators’ ICT Kits Based on rRT-PCR Ct Value Categories
To determine the diagnostic performance characteristics of the test kits in comparison with viral load, the cycle threshold (Ct) values were classified into 19.00 – 29.99, 30.00 – 34.99 and >35.00 to determine the threshold at which the test kits would have the best performance.
The results show that the DG Rapid and SD Rapid kits had higher sensitivity and Cohen’s kappa coefficient than the SS Rapid kit in detecting SARS-CoV-2 across all Ct value categories. However, all three kits showed high specificity and PPV in all Ct value categories. Specifically, Cohen’s kappa coefficient indicated substantial or excellent agreement between the ICT kits and rRT-PCR results at lower Ct values (19.00 - 29.99 and 30.00 - 34.99) for the DG Rapid and SD Rapid kits, but only good agreement for the SS Rapid kit. However, for Ct values >35.00, all three kits had poor agreement with rRT-PCR.