Patient characteristics at baseline.

Site A = Maastricht, Site B = Sittard, FEV1 = forced expiratory volume in one second, SD = Standard Deviation, ICS = Inhaled Corticosteroids, ACQ = Asthma Control Questionnaire, IQR = Inter Quartile Range, PAQLQ = Pediatric Asthma Control Quality of Life Questionnaire, FeNO = Fractional exhaled Nitric Oxide. * Six children did not use ICS at baseline. † PC20: concentration of histamine inducing a 20% drop in FEV1. ‡ Atopy is defined as a positive Phadiatop (Phadia, Uppsala, Sweden), or RAST, or a positive allergen skin test. Patient characteristics at baseline.