Diagnostic accuracy of sars-cov-2 antigen rapid test compared to real time pcr in ped

ABSTRACT

Background: The accuracy of rapid antigen tests (RAT) SARS-CoV-2 for in children is unknown. Our aim was to determine the diagnostic accuracy and concordance of the RAT PanBioTM (Abbott) compared to RT-PCR in nasopharyngeal smear (NPS) samples, in symptomatic pediatric population. Methods: This is a descriptive, retrospective, multicentre clinical study nested in a prospective, observational, multicenter cohort study. We included pediatric patients aged 0 to 16 years with symptoms consistent with COVID-19 of ≤5 days of evolution, attended in the Emergency Departments of the seven centers involved. A total of two consecutive NPS were obtained from each patient one was employed to perform the RAT and the other to perform RT-PCR. Sample size for a non-inferiority study was calculated considering 80% power, for a 5% prevalence and a 90% sensitivity, using RT-PCR as the gold standard reference. A confusion matrix was displayed. Non-inferiority of sensitivity and specificity between diagnostic tests was assessed using the McNemar's test. The agreement between the two methods was calculated using Cohen's kappa index. Results: A total of 1620 patients were tested in 7 hospitals. The overall sensitivity for RAT PanBioTM was 45.4% (95%CI, 34.1-57.2), and specificity was 99.8% (95%CI, 99.4-99.9) (Figure 1). The positive predictive value (PPV) for this 4.8% prevalence was 92.5% (95%CI, 78.6-97.4). The negative predictive value was 97.3 % (95%CI, 96.8-97.8). Positive likelihood ratio (PLR) was high - 233.8 (IC 95%, 73.5-743.3), and negative likelihood ratio (NLR) was low - 0.54 (95%CI, 0.44-0.67). Conclusion: Compared to RT-PCR, the sensitivity of the RAT PanBioTM was low in children with <5 days of symptoms of COVID-19. The specificity and PLR were good, and the NLR and concordance with RT-PCR were only moderate. These results suggest that the test is very good when the result is positive, and that the test has only a limited value when the result is negative. In relation with screening and public health policy, these results should be interpreted considering also rapidness, availability and false positives ratio compared to RT-PCR or other tests.