Abstract Rationale Bronchiectasis is a heterogeneous condition with various underlying diseases, including infections, genetic disorders, inflammatory diseases, and chronic lung disease. Its clinical presentation and etiology differ across regions and ethnic groups, and in many cases, the cause remains unidentified. Current guidelines, such as those from the British Thoracic Society and the European Respiratory Society, emphasize identifying treatable traits and underlying diseases to guide appropriate management. In Japan, limited epidemiological data has hindered a comprehensive understanding of bronchiectasis, including its underlying diseases. This study aimed to address this gap by describing the clinical characteristics of people in Japan with newly diagnosed bronchiectasis, both overall and by the underlying disease. Methods In this retrospective observational study, people with newly diagnosed bronchiectasis (ICD-10: J47.x or Q33.4 or disease code: 8833040) were identified between April 2008 and June 2024 using a Japanese hospital-based claims database that includes medical records spanning all age groups of approximately 43 million people (Medical Data Vision Co., Ltd. Tokyo). To enhance the accuracy of bronchiectasis diagnosis, inclusion required ≥1 of the following: (1) hospitalization for bronchiectasis, (2) chest computed tomography imaging within 90 days prior to diagnosis of bronchiectasis or on diagnosis date, or (3) ≥2 outpatient visits with a bronchiectasis diagnosis in different months. Then, each patient was stratified by specific underlying diseases associated with bronchiectasis, using an existing algorithm designed to increase specificity by excluding secondary infection caused by nontuberculous mycobacteria (NTM), and their demographics and clinical characteristics were investigated. Results A total of 104,142 people with bronchiectasis were identified (65.2% female, 34.8% male), with a mean age of 72.1 years (standard deviation SD: 13.16), mean body mass index of 20.1 (SD: 4.07), mean Bronchiectasis Aetiology and Comorbidity Index score of 4.25 (SD: 5.17), and 21,167 people (20.3%) had ≥1 exacerbation during the previous year or at the time of diagnosis. Most cases of bronchiectasis were idiopathic (58,248 55.9%). Common underlying diseases were post-infectious (13,943 13.4%), NTM pulmonary disease (11,486 11.0%), connective tissue diseases (CTDs; 6,484 6.2%), chronic obstructive pulmonary disease (COPD; 4,934 4.7%), and asthma (3,990 3.8%). Conclusions This first study describes clinical characteristics and underlying diseases of bronchiectasis using a large Japanese hospital-based database. Post-infectious, NTM pulmonary disease, CTD, COPD, and asthma were identified as common underlying diseases, with most cases being idiopathic. Notably, 20.3% of people with newly diagnosed bronchiectasis had experienced ≥1 exacerbations within the previous year. This abstract is funded by: Boehringer Ingelheim (Nippon)
Morimoto et al. (Fri,) studied this question.