Diagnostic accuracy of a novel blood (1→3)-β-D-glucan colourimetric assay for invasive fungal diseases: The β-glucan single M30 test WAKO

Abstract Invasive fungal diseases (IFDs) are a major cause of morbidity and mortality in immunocompromised patients. (1→3)-β-D-glucan (BDG) is a fungus-derived biomarker used for IFD diagnosis. We aimed to evaluate the diagnostic performance of a novel rapid colourimetric assay, the β-glucan single M30 test WAKO (M30), and compare its performance with the conventional turbidimetric β-glucan test WAKO (GT). We retrospectively analysed plasma samples collected from 1289 patients at Kyoto University Hospital. IFD diagnoses were based on the European Organization for Research and Treatment of Cancer/Mycoses Study Group criteria, excluding BDG. Forty-one patients had confirmed IFDs (22 with invasive candidiasis, 11 with invasive aspergillosis, 6 with Pneumocystis pneumonia, and 2 with other IFDs). The area under the receiver operating characteristic (AUROC) of the M30 assay was 0.892 (95% confidence interval [CI], 0.836–0.949). At an optimal cutoff of 6.7 pg/ml, its sensitivity was 0.732 (95% CI, 0.571–0.858), specificity was 0.990 (95% CI, 0.889–0.922), positive predictive value was 0.204 (95% CI, 0.142–0.278), and negative predictive value was 0.990 (95% CI, 0.983–0.995). For a subset of 537 samples, comparative analysis between M30 and GT was performed. The AUROC for the M30 and GT assays was 0.899 and 0.868, respectively (P = .285). At a cutoff of 11.0 pg/ml, the sensitivity was 72.2% for both assays, and the specificity was 93.5% vs. 93.3% (P = 1.000). The M30 assay demonstrated comparable diagnostic performance to the GT assay, with a shorter assay time that may facilitate earlier clinical decision-making in patients with suspected IFD.