The Performance of Antigen-Detecting Rapid Diagnostic Test Among Covid-19 Outbreaks in North-Eastern Peninsular Malaysia

Background and aims: accurate and timely diagnosis is crucial for coronavirus disease 2019 (covid-19) outbreaks. antigen-detecting rapid diagnostic tests (ag-rdts) are easily accessible and affordable, producing rapid results. they are an alternative to the limited gold-standard real-time reverse-transcription polymerase chain reaction (rrt-pcr) tests. this study assessed the performance of ag-rdts for covid-19 outbreaks in institutional settings with high disease prevalence in kelantan state, malaysia. methods: this study analyzed a total of 303 individuals from five institutional outbreaks with paired nasopharyngeal specimens tested for covid-19 by ag-rdts and rrt-pcr. the diagnostic performance of ag-rdts was evaluated through rrt-pcr as the gold standard based on cycle threshold (ct) value, disease prevalence, and manufacturers. results: there was a moderate agreement between ag-rdts and rt-pcr (κ = 0.603; 95% ci: 0.520- 0.686; p < 0.001). the overall specificity was 97.9% (95% ci: 94.1%-99.6%), sensitivity was 63.3% (95% ci: 55.3%-70.8%), accuracy ag-rdts was 81.2% (95% ci: 76.4%-85.5%), while positive and negative predictive value was 96.6% (95% ci: 90.2%-98.9%) and 74.1% (95% ci: 70.0%-77.9%), respectively. further, lower median ct was reported in 100 (33.0%) true-positive cases compared to 58 (19.1%) false-negative cases (20.3 vs 31.4, p < 0.001). the sensitivity was higher (p < 0.001) in those with high viral load (ct value ≤ 25.0) with better performance and a prevalence > 10%. in addition, no significant difference was observed between the studied manufacturers. conclusion: the ag-rdts performed well in diagnosing covid-19 among outbreaks with higher viral load and disease prevalence. high-risk cases tested negative by ag-rdts may have low viral load and require confirmation by rrt-pcr.