Comparative Evaluation of Rapid Antigen Detection Assay and RT-PCR for SARS-CoV-2 Diagnosis in a Tertiary Care Setting

Introduction: COVID-19, caused by SARS-CoV-2, underscored the need for fast, reliable diagnostics.While RT-PCR remains the gold standard, it is time-consuming and requires specialised resources, delaying decisions.Rapid antigen detection tests (RADTs) offer quicker results and ease of use, especially in resource-limited settings, though they have lower sensitivity than RT-PCR, particularly in asymptomatic cases.This study aimed to compare the diagnostic performance of RADTs and RT-PCR in a tertiary care setting.Materials and Methods: This analysis was carried out at PJMC (Phulo Jhano Medical College Hospital, Jharkhand) retrospectively.Department of Microbiology, Jharkhand.Nasopharyngeal and oropharyngeal swabs from adult and paediatric patients were collected for RT-qPCR and RADTs.For RT-qPCR, RNA was extracted and amplified using standard protocols, and results were considered positive if Ct values pertaining to the N and E genes were 35.For RADTs, testing followed the manufacturer's guidelines, with results interpreted within 30 minutes.Predictive values, specificity and sensitivity were computed, and agreement with RT-qPCR was assessed using Cohen's Kappa coefficient.Results: Out of 180 samples, the RADT showed a sensitivity of 76.19% and specificity of 100%.Sensitivity was greater in patients with symptoms (80.95%) as opposed to those without symptoms (57.3%).The overall accuracy was 86.11%, with strong agreement observed among symptomatic cases (Kappa = 0.84). Conclusion:The RADT demonstrated excellent specificity and good sensitivity, particularly in symptomatic patients, making it a valuable tool for rapid diagnosis in clinical settings.However, its lower sensitivity among asymptomatic patients underscores the need for confirmatory RT-PCR testing, especially in cases of known exposure.