TABLE 1.

“Treatable traits” of bronchiectasis

Trait	Main diseases that share the trait	Clinical features	Laboratory/physiological features	Targeted treatment
Chronic infection	Protracted bacterial bronchitis	Chronic wet cough	Growth of pathogens in respiratory secretions	Antimicrobials
	Chronic bronchitis (COPD)
Ciliary dyskinesia	PCD	Young age of symptom onset, chronic otitis media, situs abnormalities, male infertility (asthenospermia), sinusitis	Low nasal NO, electron microscopic abnormalities, abnormal ciliary beating pattern	Inhaled saline, airway clearance, ongoing trial of ENaC inhibition
	Secondary ciliary dyskinesia#
CFTR dysfunction/deficiency	CF	Young age of symptom onset, pancreatitis, malnutrition, bowel obstruction, male infertility (azoospermia), sinusitis	Elevated sweat chloride, characteristic electrophysiological abnormalities, CFTR mutations on two alleles	CFTR modulators
	CFTR-related disorder
	Secondary CFTR dysfunction#
Immune deficiency	Primary immune deficiencies	Young age of symptom onset, infection in extrapulmonary sites	Immunoglobulin deficiencies, impaired tests of immune function	IVIG
	Secondary immune deficiencies	Haematological malignancies
Systemic inflammation	Rheumatoid arthritis	Symmetric arthritis, morning stiffness	Rheumatoid factor	DMARDs, CS, anti-TNF-α
	IBD	Bloody diarrhoea, weight loss, GI ulceration	Endoscopic appearance and histology	Aminosalicylates, CS, anti-TNF-α
Eosinophilic inflammation	Asthma	Seasonality	Airway reversibility	ICS, bronchodilators, anti-IgE, anti-IL-5
	CRS	Chronic nasal discharge, loss of smell, facial pain	Sinus inflammation on endoscopy, sinus CT
	ABPA	Wheeze, mucus plugs	Elevated IgE, Aspergillus spp. sensitisation
Gastro-oesophageal reflux	GORD	Symptoms of heartburn and reflux	Endoscopic, motility and imaging studies	Behavioural measures, proton-pump inhibitors, surgery

Examples of features of bronchiectasis that define a subgroup of patients. These may be viewed as “treatable traits” and some are shared with other disease entities. CFTR: cystic fibrosis transmembrane regulator; PCD: primary ciliary dyskinesia; NO: nitric oxide; ENaC: epithelial sodium channel; CF: cystic fibrosis; IVIG: intravenous immunoglobulins; DMARDs: disease modifying antirheumatic drugs; CS: corticosteroids; TNF: tumour necrosis factor; IBD: inflammatory bowel disease; GI: gastrointestinal; ICS: inhaled corticosteroids; Ig: immunoglobulin; IL: interleukin; CRS: chronic rhinosinusitis; CT: computed tomography; ABPA: allergic bronchopulmonary aspergillosis; GORD: gastro-oesophageal reflux disorder. ^#: may be induced by smoking.