Evaluation of the performance of the Associates of Cape Cod STATâ„¢ assay for the diagnosis of invasive fungal disease in critical-care patients with COVID-19.

White, P Lewis; Price, Jessica S; Backx, Matthijs

During the COVID-19 pandemic, there have been increasing reports of invasive fungal disease (IFD) in critical-care, where rapid access to (1-3)-β-D-Glucan (BDG) testing may have enhanced diagnosis. The potential benefit of rapidly accessible BDG results is limited by local availability of BDG testing, with low demand resulting in testing being performed in specialist centres. The recent release of the Associates of Cape Cod STAT™ assay provides a simple, low-throughput BDG platform, potentially increasing accessibility. During the pandemic, BDG testing using the Fungitell assay (FA) was a critical component of screening for IFD in our critical-care. The performance of the STAT™ was retrospectively determined through a case/control study of 107 serum samples from critical-care COVID-19 patients with IFD defined according to international guidelines. The STAT™ demonstrated excellent qualitative (observed agreement 97.2%; Kappa: 0.94) and quantitative (Spearman's coefficient: 0.8962) agreement with the FA. Sample positivity was greater (P<0.0001) in samples from cases (67.7%) versus controls (6.1%). Using the manufacturer's threshold (≥1.2) sensitivity/specificity for the detection of proven/probable IFD was 67.9%/93.9%, respectively. Using a lower positivity threshold of ≥0.87, increased sensitivity to 71.4%, without compromising specificity. When the STAT™ BDG index was >2.86 specificity was 100%. The STAT™ provides a simple, comparable alternative to the FA for detecting BDG. Sensitivity is moderate and specificity is excellent for the diagnosis of IFD in the critical-care COVID-19 patient. The potential for enhancing access to BDG testing through the uptake of STAT™ at centres where FA is not available is beneficial, especially during the COVID-19 pandemic.