Clinical evaluation of two different (1,3)-β-D-glucan assays for diagnosis of invasive fungal diseases: A retrospective cohort study

Background: Early diagnosis of invasive fungal diseases (IFDs) remains a major challenge in routine clinical practice. Objectives: The aim of this retrospective cohort study was to evaluate the diagnostic performance of the fungal biomarker (1,3)-ss-d-glucan (BDG) using the beta-Glucan test (GT) and the well-established Fungitell assay (R) (FA) in real-life clinical practice. Patients/Methods: We included 109 patients with clinical suspicion of IFD who were treated at Jena University Hospital, Germany, between November 2018 and March 2019. The patients were classified according to the latest update of the EORTC/MSG consensus definitions of IFD. The first serum sample of every patient was analysed for BDG using the FA and the GT, respectively. Results: Fifty-six patients (51.4%) had at least one host factor for IFD. In patients with proven (n = 11) or probable IFDs (n = 20), median BDG concentrations were 145.0 pg/ml for the FA and 5.1 pg/ml for the GT, respectively. A positive test result of both BDG assays at manufacturer's cut-offs predicted 89.5%-98.3% of proven or probable IFD, but the sensitivity of both assays was limited: The FA identified 60.7% of IFDs (cut-off: 80 pg/ml). Reducing the GT cut-off value from 11.0 to 4.1 pg/ml increased the detection rate of IFDs from 35.5% to 54.8%. Conclusions: A positive test result of both BDG assays at manufacturer's cut-off was highly predictive for IFD, but except for Pneumocystis jirovecii pneumonia sensitivities were limited. Adjustment of the GT cut-off value equalised sensitivities of GT and FA.