“…Variables with a relative frequency below 1% were excluded. We performed EFA both by means of multiple factor analysis and principal component analysis (22). To facilitate visualization of weightings on dimensions, variables were grouped together in terms of (1) lung function (% predicted FEV 1 , % predicted FVC, FEV 1 /FVC ratio, FEF , bronchodilator reversibility, airway hyperresponsiveness), (2) markers of severity or exacerbation (symptoms within the past 4 wk, number of attacks within the last year, hospitalization), (3) family history, (4) comorbidities and atopy (rhinitis, eczema, sensitization, % eosinophils, total IgE); (5) environmental factors (exposure to tobacco smoke, pet ownership), (6) asthma medication (ICS, LABA, montelukast, and any combination), and (7) general characteristics (age, sex, BMI, age of onset of wheeze).…”