title: An analysis of etiology, causal pathogens, imaging patterns, and treatment of Japanese patients with bronchiectasis.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Pulmonary Medicine, National Hospital Organization Matsue Medical Center, 8-31, 5 cho-me, Agenogi, Matsue, Shimane 690-8556, Japan. Electronic address: toru.kadowaki@mmedc.jp.
authors.forename: Toru
authors.initials: T
authors.lastname: Kadowaki
authors.affiliation: Department of Pulmonary Medicine, National Hospital Organization Matsue Medical Center, 8-31, 5 cho-me, Agenogi, Matsue, Shimane 690-8556, Japan. Electronic address: shuichi.yano@mmedc.jp.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Yano
authors.affiliation: Department of Pulmonary Medicine, National Hospital Organization Matsue Medical Center, 8-31, 5 cho-me, Agenogi, Matsue, Shimane 690-8556, Japan. Electronic address: kiryo731@aol.com.
authors.forename: Kiryo
authors.initials: K
authors.lastname: Wakabayashi
authors.affiliation: Department of Pulmonary Medicine, National Hospital Organization Matsue Medical Center, 8-31, 5 cho-me, Agenogi, Matsue, Shimane 690-8556, Japan. Electronic address: kanako.kobayashi@mmedc.jp.
authors.forename: Kanako
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Department of Pulmonary Medicine, National Hospital Organization Matsue Medical Center, 8-31, 5 cho-me, Agenogi, Matsue, Shimane 690-8556, Japan. Electronic address: wsmt31399@leto.eonet.ne.jp.
authors.forename: Shigenori
authors.initials: S
authors.lastname: Ishikawa
authors.affiliation: Department of Pulmonary Medicine, National Hospital Organization Matsue Medical Center, 8-31, 5 cho-me, Agenogi, Matsue, Shimane 690-8556, Japan. Electronic address: masahiro.kimura@mmedc.jp.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kimura
authors.affiliation: Department of Pulmonary Medicine, National Hospital Organization Matsue Medical Center, 8-31, 5 cho-me, Agenogi, Matsue, Shimane 690-8556, Japan. Electronic address: toshikazu.ikeda@mmedc.jp.
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Ikeda
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People; D001987:Bronchiectasis / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology / Q000628:therapy; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011550:Pseudomonas aeruginosa / Q000472:pathogenicity*; D012189:Retrospective Studies; D013577:Syndrome; D014057:Tomography, X-Ray Computed
keywords: Bronchiectasis (BE); Cystic bronchiectasis; Etiology; Exacerbation