Description

Bronchiectasis is an irreversible syndrome with typical symptoms of chronic productive cough and recurrent exacerbations and with characteristic findings on cross-sectional imaging of bronchial wall dilation and thickening.

Epidemiology

Incidence

• Overall annual incidence in U.S. adults estimated to be 29 cases per 100,000
• Widespread vaccination and improved recognition and treatment of childhood respiratory disease has led to decreased incidence among U.S. children.
  • Incidence may be higher among indigenous or socioeconomically disadvantaged groups.

Prevalence

• Overall prevalence estimated to be 139 per 100,000 among U.S. adults
• Higher among women (180 per 100,000) than men (95 per 100,000)
• Prevalence increases with age: 562 per 100,000 among U.S. seniors aged >65 years
• Global estimates of prevalence in children ranges from 0.2 to 735 cases per 100,000.
  • Large variability exists among different populations of children.
  • Populations with higher prevalence include children with primary immune deficiencies, chronic aspiration, primary ciliary dyskinesia, airway malformations, and children in low-income countries.

Etiology and Pathophysiology

• Bronchiectasis is sometimes identified as an isolated pulmonary diagnosis.
• Often arises as a complication of other inherited or acquired disease states
• Vicious cycle hypothesis:
  • An initial pulmonary insult causes airway inflammation, dysfunction, and structural disease.
  • Dysfunctional airways are further impaired in their ability to clear infections.
  • A pattern of lung damage/inflammation and progressive airway dysfunction is established, leading to clinical decline.
• Neutrophil extracellular traps (NETs) and neutrophil elastase are thought to play an important role.
  • Higher levels/activity of these markers correlate with disease activity and may serve as potential therapeutic targets (1).

Risk Factors

Conditions/exposures which cause impaired host defenses, altered tracheobronchial anatomy, airway inflammation, and airway clearance all predispose to development of bronchiectasis.

General Prevention

• Routine immunization against respiratory infections (pertussis, measles, Haemophilus influenzae type B (HIB), influenza, and Streptococcus pneumonia)
• Early recognition and treatment of conditions which can lead to bronchiectasis
• Genetic counseling for patients with inheritable conditions which predispose to bronchiectasis who wish to conceive
• Smoking cessation

Commonly Associated Conditions

• Prevalence of conditions associated with bronchiectasis based on U.S. data published in 2017:
  • Pneumonia (68%)
  • GERD (47%)
  • Asthma (29%)
  • Chronic obstructive pulmonary disease (COPD) (20%)
  • Any rheumatologic disease (8%)
  • Immunodeficiency (5%)
  • History of tuberculosis (TB) (4%)
  • Inflammatory bowel disease (3%)
  • Primary ciliary dyskinesia (3%)
• Other conditions which have been associated with bronchiectasis include:
  • Allergic bronchopulmonary aspergillosis (ABPA)
  • Chronic rhinosinusitis
  • Congenital abnormalities of the airways (e.g., tracheobronchomalacia)
  • α₁-Antitrypsin deficiency