Diagnostic Accuracy of SARS-CoV-2 Rapid Antigen Testing in a Pediatric Population: Children are Not Little Adults

Information on the use of antigen-based SARS-CoV-2 rapid antigen tests (RAT) in children is limited. RATs have been used more frequently, because they are easily applicable, inexpensive, and can be easily performed at home without the need for special equipment. This study was designed to assign the diagnostic test accuracy of the SARS-CoV-2 RAT in daily clinical practice in children.

One thousand forty-two pediatric patients (aged 1 month - 18 years) who presented to the pediatric COVID-19 outpatient clinic of our hospital between January 2021 and June 2022 and met the inclusion criteria were included in this study. Nasopharyngeal samples were taken from the patients at the same visit, first for reverse transcription polymerase chain reaction (RT-PCR) and then for RAT.

The data of all patients with RT-PCR positivity (n = 314) and additionally 14 patients with RAT positivity were analyzed in depth. The overall sensitivity and specificity were 62.1% (95% CI: 56.4 - 67.4) and 98% (95% CI: 96.7 - 98.9), respectively. The positive predictive value (PPV) and the negative predictive value (NPV) in this pediatric study were 93.3% and 85.7% (95% CI: 88.7 - 96.1 and 83.1 - 87.9), respectively. Considering the Ct values, which are indirect indicators of viral load, it was observed that the sensitivity of the rapid antigen test increased at low Ct values. The sensitivity increased to 75.1% (95% CI: 67.9 - 81.1) in patients with a Ct value of < 25. The specificity was 92.7% (95% CI: 90.7 - 94.3), PPV was 67.8% (95% CI: 60.7 - 67.8) and the NPV was 94.7% (95% CI: 93.0 - 96.1) in patients with a Ct value < 25. When the patients were evaluated according to their symptomatic/asymptomatic status, the difference between the diagnostic performance of the RAT test was found to be statistically significant (p = 0.006).

In our study, it was found that the sensitivity of RATs in pediatric patients was lower than in adults. Our results also showed that children are not small adults, and the sensitivity of the test was higher, especially in symptomatic patients and patients with high viral load. To obtain more accurate results, we believe that performing the test in the first 3 days of symptoms will give more accurate results.