Evaluation of antigen based rapid diagnostic test in comparison to RT PCR in diagnosis of Sars CoV2 with respect to duration of illness and Ct value of corresponding RT PCR

Background: SARS-CoV-2 is the third highly pathogenic corona virus introduced into mankind after Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) and Middle East Respiratory Syndrome coronavirus (MERS-CoV) in twenty-first century for which the development and validation of rapid and easy-to-perform diagnostic methods are of high priority. Objective: In this study we evaluated performance characteristics of RAT, the STANDARD Q COVID19 Ag by SD-Biosensor for rapid detection of SARS CoV 2. Material and methods: Samples were collected from 1168 patients and we performed both RAT and RT PCR and the results of RAT were compared with that of RT PCR as gold standard. Result: Detection rates of SARS CoV-2 by RAT and RT-PCR were 19.17% and 29.53%, respectively; false positivity rate was 2.67%.False positive and false negative rate was 2.6% and 13.45% respectively.RAT sensitivity, specificity, negative and positive predictive values were 63.18%, 99.27%, 97.32% and 86.54% respectively. Statistical analysis considered the calculation of sensitivity, specificity, positive predictive value, negative predictive value using standard formulae. Conclusion: A high sensitivity, specificity, positive predictive value and fairly high negative predictive value of RAT might prove to be promising in situations where pre-test probability of having infection is high