[Diagnostic performance of two antigen-tests compared to one PCR-Test to detect SARS-CoV-2 in an emergency department and emergency service].

Background: In the German hospital landscape and emergency care the COVID-19 pandemic was a stress test. Emergency medical health care in Germany is ensured by the supply chain between prehospital emergency rescue and clinical emergency care in the emergency rooms. In hospitals and emergency care settings a rapid, simple, accurate, and cost-effective test is needed to identify SARS-CoV‑2. In the central emergency department it is important to strictly separate patients with suspected COVID-19 from non-infected emergency persons.

Methods: Given the background mentioned above, the performance of antigen tests in the ambulance service of the city Jena and the central emergency department of the university hospital Jena was analysed and in addition verified by using the RT-PCR gold standard. Several multiple testing procedures were performed by using antigen tests in the ambulance service and the central emergency department, and by using one or both of these antigen tests followed by the RT-PCR test. A total of 980 patients were included in the study over a two-month period (October/November 2022).

Results: The average age of all patients was 65 years. More than half of the actively treated patients came from the city of Jena. The sensitivity and specificity of the antigen tests were 66.7% and 99.2% in the clinical setting (the central emergency department) and 68.8% and 96.7% in the prehospital setting (in the ambulance service) compared to RT-PCR. In the prehospital setting the sensitivity of the antigen testing was slightly higher (2%) than the clinical antigen testing. Regarding the parallel testing, 6% of antigen tests had a false negative SARS-CoV‑2 antigen test result in the ambulance service and 4.6% of antigen tests had a false negative SARS-CoV‑2 antigen test result in the central emergency department. The false-negative antigen tests, and thus the potentially unrecognized individuals, were further reviewed by considering the Ct-value.

Conclusion: The use of antigen testing in the ambulance service and the emergency department can lead to a quick classification of COVID and non-COVID areas of an emergency department. The measurement accuracy of antigen testing in the ambulance service and central emergency department is not equivalent to the RT-PCR. Nevertheless, antigen testing is a useful initial screening tool for early detection of SARS-CoV‑2 in prehospital and clinical settings. Dual antigen testing may be useful for more accurate diagnosis of the SARS-CoV‑2 pathogen.