FebriDx point-of-care test in patients with suspected COVID-19: a pooled diagnostic accuracy study

Urwin, S. G.; Lendrem, B. C.; Suklan, J.; Green, K.; Graziadio, S.; Buckle, P.; Dark, P. M.; Gordon, A. L.; Lasserson, D. S.; Nicholson, B.; Price, D. A.; Reynard, C.; Wilcox, M. H.; Prestwich, G.; Tate, V.; Clark, T. W.; Reddy, R. V.; Body, R.; Allen, A. J.

Background: Point-of-care (POC) tests for COVID-19 could relieve pressure on isolation resource, support infection prevention and control, and help commence more timely and appropriate treatment. We aimed to undertake a systematic review and pooled diagnostic test accuracy study of available individual patient data (IPD) to evaluate the diagnostic accuracy of a commercial POC test (FebriDx) in patients with suspected COVID-19. Methods: A literature search was performed on the 1st of October 2020 to identify studies reporting diagnostic accuracy statistics of the FebriDx POC test versus real time reverse transcriptase polymerase chain reaction (RT-PCR) testing for SARS-CoV-2. Studies were screened for risk of bias. IPD were sought from studies meeting the inclusion and exclusion criteria. Logistic regression was performed to investigate the study effect on the outcome of the RT-PCR test result in order to determine whether it was appropriate to pool results. Diagnostic accuracy statistics were calculated with 95% confidence intervals (CIs). Results: 15 studies were screened, and we included two published studies with 527 hospitalised patients. 523 patients had valid FebriDx results for Myxovirus resistance protein A (MxA), an antiviral host response protein. The FebriDx test produced a pooled sensitivity of 0.920 (95% CI: 0.875-0.950) and specificity of 0.862 (0.819-0.896) compared with RT-PCR, where there was an estimated true COVID-19 prevalence of 0.405 (0.364-0.448) and overall FebriDx test yield was 99.2%. Patients were tested at a median of 4 days [interquartile range: 2:9] after symptom onset. No differences were found in a sub-group analysis of time tested since the onset of symptoms. Conclusions: Based on a large sample of patients from two studies during the first wave of the SARS-CoV-2 pandemic, the FebriDx POC test had reasonable diagnostic accuracy in a hospital setting with high COVID-19 prevalence, out of influenza season. More research is required to determine how FebriDx would perform in other healthcare settings with higher or lower COVID-19 prevalence, different patient populations, or when other respiratory infections are in circulation.