Bronchiectasis

Description

• Bronchiectasis is an irreversible dilatation of ≥1 airways accompanied by recurrent transmural bronchial infection/inflammation and chronic mucopurulent sputum production.
• It may be focal or diffused.

Epidemiology

• Predominant age: most commonly presents in 6th decade of life
• Predominant sex: female > male (1)

Incidence

• Incidence has decreased in the United States for two reasons:
  • Widespread childhood vaccination against pertussis
  • Effective treatment of childhood respiratory infections with antibiotics
• Among children, incidence may be higher in indigenous or socioeconomically disadvantaged group (2).

Prevalence

• In the United States, prevalence estimated to be 139/100,000 (3)
• Higher among women versus men (180 vs. 95/100,000) and to increase substantially with age (from 7/100,000 to 812/100,000 aged 34 and ≥75 years (3)

Etiology and Pathophysiology

• Frequently idiopathic
• Chronic infections (PTB), autoimmune disease, genetic causes (cystic fibrosis (CF)), chronic obstructive pulmonary disease (COPD), connective tissue disease, allergic bronchopulmonary aspergillosis (ABPA) (4)
• Vicious circle hypothesis: Transmural infection, generally by bacterial organisms, causes inflammation and obstruction of airways. Damaged airways and dysfunctional cilia foster bacterial colonization, which leads to further inflammation and obstruction.

Risk Factors

• Nontuberculous mycobacterial infection is both a cause and a complication of non-CF bronchiectasis.
• Severe respiratory infection in childhood (measles, adenovirus, influenza, pertussis, or bronchiolitis)
• Systemic diseases (e.g., rheumatoid arthritis and inflammatory bowel disease)
• Chronic rhinosinusitis
• Recurrent pneumonia
• Aspirated foreign body
• Immunodeficiency
• Congenital abnormalities

General Prevention

• Routine immunizations against pertussis, measles, Haemophilus influenzae type B, influenza, and pneumococcal pneumonia
• Genetic counseling if congenital condition is etiology
• Smoking cessation

Commonly Associated Conditions

• Mucociliary clearance defects
  • Primary ciliary dyskinesia
  • Young syndrome (secondary ciliary dyskinesia)
  • Kartagener syndrome
• Other congenital conditions
  • α₁-Antitrypsin deficiency
  • Marfan syndrome
  • Cartilage deficiency (Williams-Campbell syndrome)
• COPD
• Pulmonary fibrosis, causing traction bronchiectasis
• Postinfectious conditions
  • Bacteria (H. influenzae and Pseudomonas aeruginosa)
  • Mycobacterial infections (tuberculosis [TB] and Mycobacterium avium complex [MAC])
  • Whooping cough
  • Aspergillus species
  • Viral (HIV, adenovirus, measles, influenza virus)
• Immunodeficient conditions
  • Primary: hypogammaglobulinemia
  • Secondary: ABPA, posttransplantation
  • Sequelae of toxic inhalation or aspiration (e.g., chlorine, luminal foreign body)
• Rheumatic/chronic inflammatory conditions
  • Rheumatoid arthritis
  • Sjögren syndrome
  • Systemic lupus erythematosus
  • Inflammatory bowel disease
• Miscellaneous
  • Yellow nail syndrome