An analysis of etiology, causal pathogens, imaging patterns, and treatment of Japanese patients with bronchiectasis

Bronchiectasis (BE), a syndrome that presents with persistent or recurrent bronchial sepsis related to irreversibly damaged and dilated bronchi, has not been well-characterized in Asians. This study aims to review the etiology, causal pathogens, imaging patterns, and treatment of BE and to define the prognostic factors for acute exacerbation in a Japanese population.

We performed a retrospective cohort study of 147 patients (104 women; median age, 73 years; range, 30-95 years) with BE at our institution using high-resolution computed tomography to identify imaging patterns and the area of pulmonary involvement.

Common BE etiologies were idiopathic (N=50 [34%]), sinobronchial syndrome (N=37 [25%]), non-tuberculous mycobacteriosis (NTM; N=26 [18%]), and previous respiratory infection (N=21[14%]). Pseudomonas aeruginosa was the most common causal pathogen (24%). Common imaging patterns were cylindrical (66%) and mixed including cylindrical pattern (47%). The median number of involved lobes was 2; 49% of the patients had ≥ 3 involved lobes, and 49% had middle lobe and left lingula dominant BE. Patients with predominantly lower lobe BE comprised 4% of the NTM group and 48% of the non-NTM group (P<0.001). In multivariate analysis, cystic BE was a predictor for frequent exacerbations in non-NTM patients (OR=7.947; P=0.004) which led to increased hospital admissions (OR=4.691; P=0.004).

Idiopathic and sinobronchial syndrome were common causes of BE. Etiology did not contribute to imaging pattern or predictors of exacerbations. Cystic BE was a predictor for frequent exacerbations in the non-NTM BE patients.