Bronchiectasis has a complex, heterogeneous pathogenesis with various aetiologies, with idiopathic bronchiectasis being the majority. This study aimed to investigate the characteristics of patients with idiopathic bronchiectasis, in comparison with post-infectious bronchiectasis. We analyzed idiopathic and post-infectious (including post-TB) bronchiectasis patients from the Korean Multicenter Bronchiectasis Audit and Research Collaboration (KMBARC) registry, a prospective cohort study (1). Among the 866 patients enrolled in the study, 346 (40.0%) patients were determined as idiopathic, 363 (41.9%) patients as post-infectious. The idiopathic group exhibited shorter disease duration of bronchiectasis, higher BMI, lower prevalence of COPD, higher prevalence of rhinosinusitis, predominance of lower lobe distribution in bronchiectasis, lower usage of regular respiratory treatment, better pulmonary function, and statistically lower bronchiectasis severity index (BSI) compared to post-infectious bronchiectasis. Multivariable logistic regression analysis was performed for the variables of gender, age, body mass index, the history of asthma, COPD, rhinosinusitis, rheumatoid arthritis and gastroesophageal reflux disease (GERD), and smoking status. A higher body mass index (odds ratio, 1.09; 95% confidence interval, 1.04-1.15) and the history of rhinosinusitis (3.10; 1.57-6.14) were associated with idiopathic bronchiectasis. Conversely, the history of COPD was associated with post-infectious bronchiectasis (0.57; 0.41-0.80). The characteristics of patients with idiopathic bronchiectasis might be a higher body mass index (BMI) and the history of rhinosinusitis in comparison with post-infectious bronchiectasis, potentially serving as exploratory clues to underlying systemic or non-pulmonary factors. Further research is needed to clarify their clinical significance.

Background: Bronchiectasis is a chronic respiratory condition characterized by permanent bronchial dilation, recurrent infections, and progressive lung damage. A subset of patients, known as frequent exacerbators, experience multiple exacerbations annually, leading to accelerated lung function decline, hospitalizations, and reduced quality of life. The aim of this study is to identify distinct phenotypes and treatable traits in bronchiectasis frequent exacerbators, since it could be crucial for optimizing patient management. Research question: Could clinically distinct phenotypes and treatable traits be identified among frequent exacerbators with bronchiectasis to guide personalized management strategies? Methods: We analysed a cohort of 56 bronchiectasis frequent exacerbator patients using 21 clinically relevant variables, including pulmonary function tests, radiological patterns, and microbiological data. Hierarchical clustering and k-means algorithms were applied to identify subgroups. Key outcomes included cluster-specific characteristics, treatable traits, and their implications for management. Results: Four distinct clusters were identified: 1. Mild, idiopathic bronchiectasis (Cluster 1): Predominantly mild disease (FACED), idiopathic etiology (93.3%), and cylindrical bronchiectasis with moderate obstruction (60%). 2. Rheumatological and NTM-associated bronchiectasis (Cluster 2): Patients with systemic inflammatory diseases (50%) and NTMever (50%) but minimal infections by Pseudomonas aeruginosa. 3. Mild, post-infective bronchiectasis (Cluster 3): Exclusively mild disease, mixed idiopathic and post-infective etiologies, and preserved lung function. 4. Severe, chronic infection phenotype (Cluster 4): Severe disease with high colonization rates of Pseudomonas aeruginosa (71.4%), advanced structural damage (57.1% varicose, 50% cystic bronchiectasis), and frequent exacerbations. Interpretation: This analysis highlights the heterogeneity of bronchiectasis and its frequent exacerbator phenotype. The treatable traits framework underscores the importance of aggressive infection control and management of airway inflammation in severe cases, while milder clusters may benefit from preventive strategies. These findings support the integration of precision medicine in bronchiectasis care, focusing on phenotype-specific interventions to improve outcomes.

Currently, there is a lack of research on multi-drug resistant Pseudomonas aeruginosa (MDR-PA) isolation in bronchiectasis-related hemoptysis. The aim of this study to analyze the risk factors for recurrent hemoptysis following bronchial artery embolization (BAE) and compare the recurrent hemoptysis-free rates between MDR-PA, non-MDR-PA, and non-PA isolation. A retrospective study was performed of patients diagnosed with idiopathic bronchiectasis-related recurrent hemoptysis who underwent BAE at an university-affiliated hospital. Patients were categorized based on PA susceptibility tests into non-PA, non-MDR-PA, and MDR-PA groups. Univariate and multivariate Cox regression were conducted to identify independent risk factors for recurrent hemoptysis. The Kaplan-Meier curves was conducted to compare recurrent hemoptysis-free rates after BAE for non-PA, non-MDR-PA, and MDR-PA. A total of 432 patients were included. 181 (41.90%) patients experienced recurrent hemoptysis during a median follow-up period of 25 months. MDR-PA isolation (adjusted hazard ratio (aHR) 2.120; 95% confidence interval (CI) [1.249, 3.597], p = 0.005) was identified as an independent risk factor for recurrent hemoptysis. Antibiotic treatment (aHR 0.666; 95% CI [0.476, 0.932], p = 0.018) reduced the risk of recurrent hemoptysis. The cumulative recurrent hemoptysis-free rates for non-PA, non-MDR-PA, and MDR-PA were as follows: at 3 months, 88.96%, 88.24%, and 75.86%, respectively; at 1 year, 73.13%, 69.10%, and 51.72%; and at 3 years, 61.91%, 51.69%, and 41.10% (p = 0.034). MDR-PA isolation was an independent risk factor of recurrent hemoptysis post-BAE. Reducing the occurrence of MDR-PA may effectively decrease the recurrence rates of hemoptysis.