Performance evaluation of the chemiluminescence immunoassay for quantitative detection of (1, 3)-β-D-glucan for diagnosis of invasive fungal diseases

To assess the performance of a fully automated chemiluminescence immunoassay (CLIA) for the quantitative detection of (1, 3)-β-D-glucan (BDG) in serum samples for the diagnosis of invasive fungal diseases (IFD) and compare the results with the photometric assay, serum samples were collected from 604 patients with clinically suspected IFD between December 2022 and September 2023. According to the 2019 EORTC/MSG guideline, patients were divided into the IFD group (comprising 43, 224, and 81 proven, probable, and possible cases, respectively) and the non-IFD group (256 cases), and BDG in serum samples was measured using both the CLIA and photometric assays. The sensitivity of the CLIA assay for invasive aspergillosis (IA), pneumocystis pneumonia (PCP), and invasive candidiasis (IC) was 88.66% (95% CI, 80.22 to 93.93%), 82.35% (95% CI, 55.80 to 92.18%) and 75.90% (95% CI, 68.54 to 82.04%), respectively, with a specificity of 97.27% (95% CI, 94.21 to 98.80%). The sensitivity of the photometric assay for IA, PCP, and IC was 89.69% (95% CI,81.44 to 94.67%), 76.47% (95% CI, 49.76 to 92.18%), and 72.89% (95% CI, 65.35 to 79.35%), respectively, with a specificity of 100.00% (95% CI, 98.16 to 100.00%). The sensitivity of the CLIA assay was superior to that of the photometric assay (79.60% vs. 77.59%) in diagnosing proven/probable/possible IFD, but the specificity was lower than that of the photometric assay (97.27% vs. 100.00%). The performance of the CLIA assay was highly consistent with that of the photometric assay, both quantitatively (rs = 0.833) and qualitatively (kappa = 0.913). Lowering the cut-off value of the CLIA assay from 90.00 to 85.23 pg/ml improved diagnostic efficiency, with a sensitivity and specificity of 80.17% and 96.88%, respectively. Overall, the diagnostic performance of the two assays was comparable, with the CLIA assay having a higher sensitivity for the diagnosis of IFD. Considering the convenience of automated analysis and point-of-care testing, the CLIA assay is a promising alternative to conventional assays for diagnosing IFD.