EVALUATION OF THE DIAGNOSTIC PERFORMANCE OF COVID-19 RAPID ANTIGEN TEST IN COMPARISON TO SARS-COV-2 REVERSE TRANSCRIPTASE POLYMERASE CHAIN REACTION

Abstract

Objective: The World Health Organization recommends reverse transcriptase polymerase chain reaction (RT-PCR) as the reference method for COVID-19 diagnosis. However, it is time- consuming, costly, and requires specialized equipment and trained personnel. Therefore, rapid antigen tests (RATs), which provide results within 15–30 minutes, have emerged as a potential alternative. The aim of the current study was to assess the diagnostic performance of the SARS-CoV-2 Rapid Antigen Test (Ref No: 9901-NCOV-01G, Roche Diagnostics) compared to RT-PCR in adult patients with COVID-19-related symptoms. Material and Methods: In this prospective observational study, 492 symptomatic adult patients, aged ≥ 18 years, were tested using simultaneous oro-nasopharyngeal swabs for RAT and RT- PCR. Diagnostic metrics were calculated, and the impact of cycle threshold (Ct) values and symptom duration on RAT performance was analyzed. Results: In total, 167 (33.9%) of 492 patients’ oro- nasopharyngeal swab samples tested by RT-PCR result were positive. Compared to RT-PCR, the sensitivity, specificity, positive and negative predictive value of RAT were 90.4% [95% confidence interval (CI): 85%-94%], 98.8% (95% CI: 96.9%-99.5%), 97.4% (95% CI: 93.6%-99%) and 95.3% (95% CI: 92.4%-97.1%), respectively. The Ct values of samples with false-negative RAT results were higher than the samples that tested positive by RAT and RT-PCR [23.93±4.40) vs. 18.42±4.56), p<0.001]. Based on the Ct values, RAT sensitivity was 96.5%, 80.5%, and 30.8% for the <22, 22-26, and >26 groups, respectively. Furthermore, as Ct values increased, RAT was less likely to detect SARS-CoV-2 infection (p<0.001). Conclusion: The SARS-CoV-2 RAT exhibited high diagnostic performance in symptomatic patients and exceeded the minimum sensitivity and specificity thresholds recommended by the World Health Organization. Although its sensitivity decreases with higher Ct values, which may reflect lower viral loads, RAT remains a valuable point-of-care tool for early detection and isolation of COVID-19 cases. Confirmatory RT- PCR testing should be considered in symptomatic patients with negative RAT results.

Keywords

• COVID-19
• diagnostic accuracy
• rapid antigen test
• SARS-CoV-2

Supporting Institution

Conflicts of Interest: The authors declare no conflicts of interest. This research received no external funding.

Ethical Statement

Ethics Committee Approval: The study protocol was approved by the Ankara University, Faculty of Medicine, Human Research Ethics Committee (Date: 14.10.2021 and Decision no: I9-591-21). Only individuals who confirmed their voluntary participation by reading and signing the informed consent form were included in the study.

Thanks

We would like to thank our volunteers, who agreed to participate in our study, Laborant Meşure Taşkan for her contributions in collecting the RAT and SARS-CoV-2 RT-PCR O-NFS samples, all the staff of the COVID-19 outpatient clinic, and the Central Molecular Microbiology Laboratory of our hospital, and Roche company for their support in providing the RAT kits used in the study.

COVID-19 Hızlı Antijen Testinin Sars-Cov-2 Reverz Transkriptaz Polimeraz Zincir Reaksiyonu İle Karşılaştırmalı Tanısal Performansının Değerlendirilmesi

Abstract

Amaç: Dünya Sağlık Örgütü, COVID-19 tanısında referans yöntem olarak reverz transkriptaz polimeraz zincir reaksiyonunu (RT-PZR) önermektedir. Ancak bu yöntem; zaman alıcı ve maliyetli olup özel donanım ve eğitimli personel gerektirmektedir. Bu nedenle, hızlı antijen testleri (HAT) potansiyel bir alternatif olarak öne çıkmıştır. Bu çalışmanın amacı, COVID-19 ile ilişkili semptomları olan erişkin hastalarda SARS-CoV-2 Hızlı Antijen Testi'nin (Ref No: 9901- NCOV-01G, Roche Diagnostics) RT-PZR ile karşılaştırmalı tanısal performansını değerlendirmektir. Gereç ve Yöntemler: Bu prospektif gözlemsel çalışmada, 492 semptomatik erişkin hastadan eş zamanlı olarak alınan oro- nazofarengeal sürüntüler HAT ve RT-PZR yöntemleriyle test edilmiştir. Tanısal ölçütler hesaplanmış ve döngü eşiği (Ct) değerlerinin ve semptom süresinin HAT performansı üzerindeki etkisi analiz edilmiştir. Bulgular: RT-PZR ile test edilen 492 hastanın 167’sinde (%33,9) oro-nazofarengeal sürüntü örnekleri pozitif bulunmuştur. RT-PZR ile karşılaştırıldığında, HAT’in duyarlılığı %90,4 [güven aralığı (GA) %95: %85–%94], özgüllüğü %98,8 (GA %95: %96,9–%99,5), pozitif prediktif değeri %97,4 (GA %95: %93,6–%99) ve negatif prediktif değeri %95,3 (GA %95: %92,4–%97,1) olarak hesaplanmıştır. Yanlış negatif HAT sonuçlarına sahip örneklerin Ct değerleri, her iki yöntemle de pozitif saptanan örneklere kıyasla daha yüksek bulunmuştur [23,93±4,40) vs. 18,42±4,56), p<0,001]. Ct değerlerine göre HAT’in duyarlılığı <22, 22–26 ve >26 grupları için sırasıyla %96,5, %80,5 ve %30,8 olarak saptanmıştır. Ayrıca, Ct değeri arttıkça HAT’in SARS-CoV-2 enfeksiyonunu saptama olasılığı anlamlı şekilde azalmıştır (p<0,001). Sonuç: SARS-CoV-2 Hızlı Antijen Testi, semptomatik hastalarda yüksek tanısal performans göstermiş ve Dünya Sağlık Örgütü tarafından önerilen minimum duyarlılık ve özgüllük eşiklerinin üzerinde bulunmuştur. Ct değerinin artmasıyla, ki bu durum viral yükün azalmasını yansıtmaktadır, testin duyarlılığı düşse de HAT COVID-19 olgularının erken saptanması ve izolasyonu açısından değerli bir başvuru testi olarak ön plana çıkmaktadır. Semptomatik hastalarda negatif HAT sonucu alınması durumunda sonucun RT-PZR testi ile doğrulanması önerilmektedir.

Keywords

• COVID-19
• tanısal doğruluk
• hızlı antijen testi
• SARS-CoV-2

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