Evaluation of a quantitative serum Aspergillus fumigatus-specific IgM assay for diagnosis of chronic pulmonary aspergillosis

Background The early diagnosis of chronic pulmonary aspergillosis (CPA) remains challenging. Currently, a new quantitative IgM antibody assay that enveloped purified galactomannan extracted from Aspergillus fumigatus as antigen was commercially available in China, but its diagnostic value remains to be established. Methods Results To evaluate the role of this commercial IgM assay for diagnosis of CPA, a multi-center prospective study was performed in 12 hospitals in Zhejiang Province, from January 1 to December 31, 2016. Adult inpatients without severe immunocompromised condition and those with persistent clinical symptoms/radiological findings >= 3 months or a consistent appearance in chest CT that was suggestive of CPA were included. The clinical data were compiled using a structured questionnaire. A total of 87 cases were enrolled, including 43 CPA. The sensitivity ranged from 16.3% to 46.5%, and the specificity from 77.3% to 95.5% when cutoffs were from 50 to 80 arbitrary unit (AU)/mL. The receiver operating characteristic analysis revealed an area under the curve of 0.627. When a cutoff of 38.12 AU/mL was applied, the sensitivity and specificity were 69.8% and 56.8%, respectively, which represents the best performance. Conclusions To our knowledge, this study was the first to evaluate this commercial A. fumigatus-specific IgM antibody assay in CPA patients in China and indicates that this IgM assay has a limited value and should not be a prior recommendation for CPA diagnosis.