Phenotypes, Risk Factors, and Mechanisms of Adult-Onset Asthma

Table 1

Background information of cluster analyses including characterization of phenotypes of adult-onset asthma.

Study	Patient	Duration of asthma (mean/median years)	Patients with early-onset asthma included	Severity levels included	Major comorbidities (other than rhinitis/atopy) included as input or outcome variables	Smokers included	Other exclusion criteria	Study setting; CS = cross-sectional; L = longitudinal (time followed)	Variables related to biomarkers included in cluster analysis
Haldar et al. 2008 [16]	(a) 184; (b) 187; (c) 68	NR	Yes	(a) Mild-to-moderate, (b-c) refractory	(b) Scores for anxiety (input), depression and hyperventilation syndrome	Ex-smokers with 10 pack-years	(c) Therapy nonadherence	(a-b) CS; (c) L (1 year)	Sputum eosinophil count
Moore et al. 2010 [15]	(d) 726	22	Yes	All	Aspirin sensitivity/polyps, pneumonia/bronchitis, sinus disease, GERD, and hypertension (all input, included in composite variables)	Ex-smokers with 5 pack-years	Age below 12 years	CS	None
Siroux et al. 2011 [19]	(e) 1895; (f) 641	NR	Yes	All	Eczema (input)	Yes	(e) Age below 20 years; (f) Children	CS (population-based)	Total IgE
Amelink et al. 2013 [3]	(g) 200	10	No	All	NSAID sensitivity (input), history of nasal polyposis, and reflux symptoms/medication	Yes if 12% FEV1 reversibility after salbutamol inhalation and normal diffusion capacity.	Respiratory symptoms or chronic lung diseases during childhood, other pulmonary diseases, or nonrelated major comorbidities, pregnancy.	CS	Sputum eosinophils, total IgE
Kim et al. 2013 [14]	(h) 724; (i) 1843	NR	Yes	All	None	Yes	(h) Subjects with destroyed lungs, bronchiectasis or lung resection, age below 18 years; (i) age below 18 years	(h) L (1 year); (i) CS	None
Newby et al. 2014 [17]	(j) 349	NR	Yes	Severe refractory	Scores for anxiety and depression, reflux history, nasal polyps, and eczema	Yes	NR	L (median 3 years)	Blood eosinophil count, total IgE
Schatz et al. 2014 [18]	(k) 3612	NR	Yes	Difficult-to-treat asthma (all)	Aspirin sensitivity, atopic dermatitis (input)	Yes, smoking history 30 pack-years	(k) Age below 12 years	L (1 year)	Total IgE
Kaneko et al. 2013 [20]	(l) 880	NR	Yes	All	None	Yes	NR	CS	Total IgE

NR = not reported, GERD = gastroesophageal reflux disease, NSAID = nonsteroidal anti-inflammatory drug, and FEV1 = forced expiratory volume in 1 second. (a), (b), and (c) Patients recruited from several different studies and sources (a = primary care, b = secondary care, c = data from a prospective clinical study), (d) SARP = the Severe Asthma Research Network, (e) ECRHSII = European Community Respiratory Health Survey, (f) EGEA2 = Epidemiological Study on the Genetics and Environment of Asthma, (g) patients recruited from hospitals in Amsterdam, (h) COREA = Cohort for Reality and Evolution of Adult Asthma in Korea, (i) SCH = Korean asthma cohort of Soonchunhyang University Asthma Genome Research Centre, (j) patients from British Thoracic Society Severe Refractory Asthma Registry, (k) TENOR = The Epidemiology and Natural History of Asthma: Outcomes and Treatment Regimens, and (l) patients recruited from University of Tsukuba Hospital, Hokkaido University Hospital, or their affiliated hospitals, Japan. Defined as age at onset 18 years.