Allergic bronchopulmonary aspergillosis in Japan: A nationwide survey

Allergic bronchopulmonary aspergillosis (ABPA) is an allergic pulmonary disease characterized by a hypersensitivity reaction to Aspergillus species colonizing the airways. The clinical characteristics of ABPA may differ depending on genetic and environmental background. We performed a nationwide survey to determine the clinical characteristics of ABPA in Japan.

In 2013, a questionnaire on physician-diagnosed ABPA/allergic bronchopulmonary mycosis was sent to 903 medical centers specializing in respiratory or allergic diseases. Cases fulfilling the following criteria were categorized as possible ABPA-central bronchiectasis (ABPA-CB): 1) presence of specific serum immunoglobulin E (IgE) antibodies or a positive skin reaction to Aspergillus, and 2) bronchiectasis or mucoid impaction in the central bronchi.

Of 499 physician-diagnosed cases reported by 132 clinical centers, 358 cases met the criteria for possible ABPA-CB. Median age of ABPA-CB onset was 57 (interquartile range, 44-68) years; later-onset disease, developing ≥50 years of age, accounted for 66% of the cases and was associated with female sex, delayed onset of asthma, and lower levels of serum IgE. A third of the patients (120 patients, 34%) exhibited low levels of serum total IgE (<1000 IU/mL). Aspergillus species were isolated from sputum in 126/213 cases (59%), and Schizophyllum commune was identified in 12 (6%) patients. During the course of the treatment, ABPA recurred in 169 (48%) cases.

This nationwide survey identified several unique clinical characteristics of ABPA in Japan, such as late-onset, relatively lower serum IgE levels, and frequent recurrences/flares.