Quantification of 1,3-β-D-Glucan by Wako β-Glucan Assay for rapid exclusion of invasive fungal infections in critical patients: a diagnostic test accuracy study.

OBJECTIVES Rapid and reliable exclusion of invasive fungal infections (IFI) by markers able to avoid unnecessary empirical antifungal treatment is still a critical unmet clinical need. We investigated the diagnostic performance of a newly available β-d-Glucan (BDG) quantification assay, focusing on the optimisation of the BDG cut-off values for IFI exclusion. METHODS BDG results by Wako β-glucan assay (lower limit of detection [LLOD] = 2.16 pg/mL, positivity ≥ 11 pg/mL) on two consecutive serum samples were retrospectively analysed in 170 patients, admitted to haematological wards (N = 42), intensive care units (ICUs; N = 80), or other wards (N = 48), exhibiting clinical signs and/or symptoms suspected for IFI. Only patients with proven IFI (EORTC/MSG criteria) were considered as true positives in the assessment of BDG sensitivity, specificity and predictive values. RESULTS Patients were diagnosed with no IFI (69.4%), proven IFI (25.3%) or probable IFI (5.3%). Two consecutive BDG values   7.7 pg/mL, could be a promising diagnostic approach to confidently rule out an IFI in both ICU and non-ICU patients. The poor specificity in the ICU setting remains a concern, due to the difficulty to interpret positive results in this fragile population.