654. Evaluation of the Febridx Host Response Point-of-Care Test to Differentiate Viral From Bacterial Etiology in Adults Hospitalized with Acute Respiratory Illness During Influenza Season

Abstract

BackgroundAntibiotics are overused in patients hospitalized with acute respiratory illness (ARI). Diagnostic uncertainty regarding microbial etiology contributes to this practice and so a host response test that can distinguish between viral and bacterial infection has the potential to reduce unnecessary antibiotic use. The FebriDx is a low cost, rapid, host response POCT that uses fingerpick blood samples to distinguish between viral and bacterial infection but has not been evaluated in hospitalized adults with ARI.MethodsWe took fingerpick blood samples from adult patients with ARI, hospitalized during influenza season, and tested them on the FebriDx. Respiratory samples were tested for viruses on the FilmArray Respiratory Panel (FARP). The FebriDx was evaluated for ease of use, failure rate and accuracy of the results (Viral, Bacterial, Negative).Results149 patients were approached and 10 patients declined fingerpick testing. A valid result was obtained from 124/139 (89%) overall. Common user comments included test failure due to difficulty of getting blood to fill the capillary tube and difficulty in interpreting the results lines due to the variability of color change. 111/124 (89%) were tested for viruses by FARP. 69/111 (62%) had viruses detected. Of 69 patients with viruses detected, 41 (59%) had influenza, 12 (17%) rhino/enterovirus and 16 (23%) other viruses. 44/69 (64%) had a viral FebriDx result. For influenza-positive patients 34/41 (83%) had a viral FebriDx result, 1/12(8%) of rhinovirus-positive patients had a viral FebriDx result and 9/16 (56%) of patients with other viruses detected had a viral FebriDx result. These are interim results. Full results for 200 patients will be available at presentation.ConclusionThe use of the FebriDx POC was associated with a failure rate of ~10% and problems with the interpretation of result lines. FebriDx was not sufficiently accurate in differentiating viral and bacterial infection when using detection of virus by PCR as the definition of viral infection; however, FebriDx had a high PPV for all viral detection and for influenza detection in this cohort and could have utility in hospital emergency departments. Disclosures All authors: No reported disclosures.

Diagnostic accuracy of the FebriDx host response point-of-care test in patients hospitalised with suspected COVID-19

“…[1][2][3][4][5] MxA is a marker of interferoninduced antiviral host response and in our previous work, the detection of MxA by FebriDx had high sensitivity for the detection of Influenza in hospitalized adults, during influenza season. 6 MxA levels are also likely to be significantly elevated in patients with COVID-19 but the diagnostic accuracy of FebriDx in this situation is currently unknown. FebriDx is a low cost, instrument-free, disposable POCT system and if sensitive for the detection of COVID-19, could be rapidly deployed across the NHS and other healthcare systems to help mitigate the long delays in diagnostic testing and provide a rapid triage tool.…”

Horses for courses? Assessing the potential value of a surrogate, point‐of‐care test for SARS‐CoV‐2 epidemic control

“…The key risk in using any POCT is of a false-negative result leading to 90%, and specificities from 78% to 88%. [13][14][15][16] However, two recent studies from the UK evaluate FebriDx specifically for screening for SARS-CoV-2 in hospital: a small-scale pilot, 5 and a study nested within a non-randomised clinical trial of molecular POCTs. 6 These studies report impressive sensitivities and specificities of 100% and 93%, and 100% and 86%, respectively.…”

“…However, reported sensitivity ranges for COVID and non-COVID patients in healthcare settings are wide. 5,6,[13][14][15][16] The test should therefore be positioned within a diagnostic algorithm, alongside other clinical and radiological markers, to optimise performance.…”

“…Studies evaluating FebriDx mostly consider performance in distinguishing viral from bacterial causes of acute respiratory illnesses in toto, in secondary care. Reported sensitivities range from 64% to 90%, and specificities from 78% to 88% 13‐16 . However, two recent studies from the UK evaluate FebriDx specifically for screening for SARS‐CoV‐2 in hospital: a small‐scale pilot, 5 and a study nested within a non‐randomised clinical trial of molecular POCTs 6 .…”

Horses for courses? Assessing the potential value of a surrogate, point-of-care test for SARS-CoV2 epidemic control

“…FebriDx offers greatest value early in the clinical course, given the absence of reliable antigen POCTs and scarcity of molecular POCTs. However, reported sensitivity ranges for COVID and non-COVID patients in healthcare settings are wide (5,6,(13)(14)(15)(16). The test should therefore be positioned within a diagnostic algorithm, alongside other clinical and radiological markers, to optimise performance.…”