Role of Aspergillus fumigatus-Specific IgE in the Diagnosis of Allergic Bronchopulmonary Aspergillosis

Introduction: Allergic bronchopulmonary aspergillosis (ABPA) has been regarded as a rare disease in China due to the lack of quantitative detection of Aspergillus fumigatus-specific IgE (sIgE). We compared the diagnostic rate of ABPA among asthma patients with or without A. fumigatus-sIgE screening tests to evaluate the benefit of the tests in diagnosing ABPA. Methods: We reviewed the detection rate of A. fumigatus-sIgE and the diagnostic rate of ABPA in 1842 asthma patients in the First Affiliated Hospital of Zhejiang University from 2014 to 2016. Additionally, we collected 144 asthma cases from November 2016 to March 2017 to detect the total serum IgE, A. fumigatus-sIgE and sIgE against mixed mold extract, the ABPA diagnostic rate of these patients was then compared with the total cohort. Total serum IgE, A. fumigatus-sIgE and sIgE against mixed mold extract were also tested in 30 patients identified with Aspergillus-positive sputum culture to analyze the incidence of ABPA. Results: Among the 1,842 asthma cases, 566 were inspected for total IgE; 308 (55.40%) were total IgE-positive and 58 (10.43%) had total IgE > 1,000 IU/mL. In contrast, only 126 cases were tested for A. fumigatus-sIgE (6.84%), and 28 had A. fumigatus-sIgE > 0.35 kUA/L (22.22%). Eleven patients were finally diagnosed with ABPA. Of 1,842 asthma patients, only 0.6% were diagnosed with ABPA if the A. fumigatus-sIgE was not detected at first. Moreover, among the 144 asthma cases that were selected for total IgE, A. fumigatus-sIgE, and sIgE against mixed mold extract screening tests, 12 had total IgE > 1,000 IU/mL (8.33%), 11 had A. fumigatus-sIgE > 0.35 kUA/L (7.64%), and 14 had sIgE against mixed mold extract > 0.35 (9.72%); 7 of these patients were confirmed as having ABPA according to the ISHAM guidelines (4.86%) but only 2 without A. fumigatus-sIgE screening test were diagnosed with ABPA (1.39%) (p = 0.000). Of the 30 Aspergillus-positive sputum culture cases, 4 had A. fumigatus-sIgE > 0.35 kUA/L (13.33%), but none was diagnosed with ABPA. Conclusions: Routine A. fumigatus-sIgE screening for asthma patients can significantly improve the diagnostic rate of ABPA.