Post-infectious (20%) | Other aetiologies of bronchiectasis should be excluded. Tuberculosis is the most common cause and is more prevalent in developing countries [162]. |
COPD (15%) | Prevalence of bronchiectasis of 29% in a cohort of patients with COPD; the most common pattern is tubular [163]. May represent primary bronchiectasis in the setting of COPD or bronchiectasis secondary to COPD. Investigation for aetiology of bronchiectasis may be warranted on a case by case basis [164]. |
Connective tissue disease (10%) | Bronchiectasis has been present in up 35% of patients with rheumatoid arthritis [165]. Patients with connective tissue disease may also have traction bronchiectasis as a result of fibrotic lung disease [166]. |
Immunodeficiency (5.8%) | Most frequent immunodeficiency is common variable immune deficiency [167]. As such, different guidelines suggest obtaining serum immunoglobulins as part of the work-up of the aetiology of bronchiectasis [154, 168]. |
Allergic bronchopulmonary aspergillosis (4.5%) | Suspect in patients with difficult to control asthma or cystic fibrosis, eosinophilia (often >500 cells·mm−3) and elevated total serum IgE levels (often >417 IU·mL−1). On chest CT, bronchiectasis tends to be central and there may be mucus plugs in central bronchi and high attenuation mucus in the bronchi. Other corroborating tests include cutaneous reactivity or specific IgE antibody to filamentous fungal antigen, precipitating antibodies or IgG antibodies against filamentous fungal antigen, and filamentous fungal growth in respiratory cultures [169]. |
Asthma (3.3%) | In one cohort, bronchiectasis was present in 67.5% of patients with severe asthma. Those with bronchiectasis are more likely to have growth of pathogens in sputum culture and consume more antibiotics. The most common type of bronchiectasis is cylindrical [170]. |
Inflammatory bowel disease (1.9%) | Most common thoracic manifestation of inflammatory bowel disease. Bronchiectasis is seen more often with ulcerative colitis [171]. |
Ciliary dysfunction (1.7%) | Primary ciliary dyskinesia is an autosomal recessive disorder that manifests as chronic rhinosinusitis, recurrent respiratory infections, male infertility and bronchiectasis. Half of all patients have defects in organ laterality [172]. |
Aspiration/oesophageal reflux (0.6%) | Gastrointestinal symptoms are common in patients with bronchiectasis [173]. There is also high prevalence of IgG against Helicobacter pylori in serum of patients with bronchiectasis [174]. Bronchiolitis may also be present with chronic aspiration [175]. |
α1-antitrypsin deficiency (0.6%) | Clinically significant bronchiectasis has been identified in 27% of patients with α1-antitrypsin deficiency. Bronchiectasis is more often tubular and in the lower lobes. Panlobular emphysema is common [176]. |
Yellow nail syndrome (0.1%) | Yellow nail syndrome is characterised by lower extremities lymphoedema, bronchiectasis, pleural effusion, and yellow nail discolouration [177]. |