Combined RT-PCR and Host Response Point-of-Care Testing in Patients Hospitalised with Suspected COVID-19: A Prospective Diagnostic Accuracy Study

• DOI: 10.1007/s40121-022-00646-4
• Publication Date: 2022-05-09T16:03:12Z
• Authors: Nathan J. Brendish; Alex R. Tanner; Stephen Poole; Kate R. Beard; Vasanth V. Naidu; Christopher T. Ma...; Nicholas J. Norton; Helen Wheeler; Laura Presland; Tristan W. Clark
• Keywords: Composite clinical reference standard; RT-PCR; 610; COVID-19; MxA; Diagnostic accuracy; 3. Good health; 03 medical and health sciences; 0302 clinical medicine; Point-of-care test; FebriDx; Original Research

RT-PCR has suboptimal sensitivity for the diagnosis of COVID-19. A composite reference standard comprising RT-PCR plus radiological and clinical features has been recommended for diagnostic accuracy studies. The FebriDx finger prick point-of-care test detects an antiviral host response protein (MxA) in 10 min. We evaluated the diagnostic accuracy of FebriDx and RT-PCR compared to a composite reference standard.Adults presenting to hospital with suspected COVID-19 were tested by FebriDx and RT-PCR. A composite reference standard was used to classify patients as having COVID-19 based on RT-PCR positivity, or RT-PCR negativity with COVID-19 radiological findings or other clinical criteria. Measures of accuracy were calculated for MxA alone, RT-PCR alone, and both combined. This study is registered with the ISRCTN (ISRCTN14966673) and has completed.A total of 478 patients were tested, with valid results in 475. Of these 475 patients, 222 (46.7%) were classified as having COVID-19; 192 (40.4%) were RT-PCR positive, and 30 (6.3%) were RT-PCR negative and diagnosed on radiological/clinical criteria. Sensitivity of FebriDx MxA vs the composite reference standard was 186/222 (83.8%, 95% CI 78.3-88.4) and was similar to the sensitivity of RT-PCR (192/222 (86.5%, 95% CI 81.3-90.7), (difference of 2.7%, 95% CI - 3.9 to 9.3, p = 0.42). The sensitivity of combined FebriDx and RT-PCR was 208/222 (93.7%) which was superior to both RT-PCR alone (difference of 9.9, 95% CI 4.1-15.9; p = 0.001) and FebriDx MxA alone (difference of 7.2, 95% CI 1.6-12.9; p = 0.011).Sensitivity of combined FebriDx and RT-PCR testing was superior to each alone for the detection of COVID-19 in hospital and may improve infection control and treatment decisions.