TABLE 1

Pulmonary treatable traits of airway diseases

Treatable traits (can coexist)	Imp.	Rec.	Diagnostic criteria	Treatment			Main expected benefit
Treatable traits (can coexist)	Imp.	Rec.	Diagnostic criteria	First choice	Efficacy	Second choice	Main expected benefit
Airflow limitation [9]	+++	+++	FEV₁/FVC <0.7 (or lower limit of normal)				S
Airway smooth muscle contraction	++	+++	Bronchodilator reversibility, peak expiratory flow variability, positive PC₂₀	Maintenance: long-acting β₂-adrenergic agonists/muscarinic antagonists; rescue: short-acting β₂-adrenergic agonists/muscarinic antagonists	+++	Inhaled corticosteroids, bronchial thermoplasty^¶	S
Loss of elastic recoil (emphysema)	+++	++	Chest computed tomography, D_LCO, compliance	Smoking cessation	+	Lung volume reduction surgery, lung transplantation, α₁-anti-trypsin replacement if deficient, valves, coils	S, P
Airway mucosal oedema	++	+	Chest computed tomography, spirometry-induced bronchoconstriction	Inhaled corticosteroids	++	Oral corticosteroids, anti-interleukin-5, -13, -4	E
Eosinophilic airway inflammation [55, 56]	+++	+++	Sputum eosinophils, blood eosinophils, F_eNO, (periostin)	Inhaled corticosteroids	+++	Oral corticosteroids, leukotriene receptor antagonists, anti-IgE, anti-interleukin-5, -13, -4	E
Chronic bronchitis	++	+++	Cough and sputum 3 months×2 years (no eosinophilic airway inflammation)	Smoking cessation	+	Carbocysteine, macrolides, roflumilast	E
Airway bacterial colonisation^#	++	++	Sputum culture, quantitative PCR	Antibiotics	++	Long-term low-dose macrolides, vaccination	E/S
Bronchiectasis^#	++	++	Chest computed tomography	Drainage	+	Macrolides, nebulised antibiotics, surgery, vaccination	E/S
Cough reflex hypersensitivity [49, 57]	++	+++	Capsaicin challenge, cough counts, cough questionnaire	Speech and language treatment [58]	+	Gabapentin [56]	S
Pre-capillary pulmonary hypertension^#	++	++	Doppler echocardiography, brain natriuretic peptide, right heart catheterisation	Long-term (domiciliary) oxygen therapy	++	Noninvasive ventilation, lung transplantation	S, E, P
Chronic respiratory failure^#
Arterial hypoxaemia	+++	+++	P_aO₂ <55 mmHg	Long-term (domiciliary) oxygen therapy	++		P
Arterial hypercapnia	+++	+++	P_aCO₂ >45 mmHg		+	Noninvasive ventilation, lung transplantation

Imp.: importance; Rec.: recognisability. Diagnostic criteria and treatments options in italics should be considered as experimental (under current investigation) or having an unfavourable risk–benefit ratio. Expected treatment benefits on: E: exacerbations (rate/severity); S: symptoms; P: prognosis. FEV₁: forced expiratory volume in 1 s; FVC: forced vital capacity; PC₂₀: provocative concentration causing a 20% fall in FEV₁; D_LCO: diffusing capacity of the lung for carbon monoxide; F_eNO: exhaled nitric oxide fraction; P_aO₂: arterial oxygen tension; P_aCO₂: arterial carbon dioxide tension. ^#: treatable traits probably best dealt with in a specialist setting; ^¶: not studied in COPD-like airway disease.