The clinical value of Aspergillus-specific IgG antibody test in the diagnosis of nonneutropenic invasive pulmonary aspergillosis

Objectives: Aspergillus-specific IgG antibody ( Asp IgG) has been successfully applied in the diagnosis of chronic pulmonary aspergillosis. We explored its value in nonneutropenic invasive pulmonary aspergillosis (IPA) by a multicenter, prospective, and controlled study. Methods: We enrolled 372 clinically suspected nonneutropenic patients with IPA from February 2015 to August 2022. After excluding 4 cases with Aspergillus colonization, the remaining 368 cases were finally confirmed as patients with IPA (n =99), or non-IPA patients (n =269) consisting of community-acquired pneumonia (n =206), tuberculosis (n =22), nontuberculous mycobacteria (n =5), lung abscess (n =6), or noninfectious diseases (n =30). Asp IgG in plasma samples was tested by enzyme-linked immunosorbent assay. Results: At cut-off value of >= 80 AU/mL, Asp IgG had much higher sensitivity (59.6% vs. 19.2%, p < 0.0001), but lower specificity (77.0% vs. 96.3%, p < 0.0001) than serum galactomannan (GM) (cut-off value of >= 1.0), and similar sensitivity (59.6% vs. 55.6%, p =0.611) but lower specificity (77.0% vs. 91.2%, p =0.001) than bronchoalveolar lavage fluid (BALF) GM (cut-off value of >= 1.0), respectively. Combination diagnosis of either positive for Asp IgG or BALF GM had higher sensitivity (81.0% vs. 55.6%, p =0.002), but lower specificity ( 75.2% vs. 91.2%, p =0.001) than BALF GM alone. The receiver operating characteristic curve showed that Asp IgG had an optimal diagnostic value when the cut-off value was 56.6 AU/ml, and the sensitivity and specificity were 77.8% and 63.9%, respectively. Discussions: The diagnostic value of Asp IgG for IPA is superior to serum GM, and a little inferior to BALF GM in nonneutropenic patients with IPA. Considering the convenience of taking blood samples, it is a good screening and diagnostic method for nonneutropenic patients with IPA, especially for those who cannot bear invasive procedures. (C) 2023 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.