Current data collected in early adulthood
At the follow-up visit in 2010, when the participants were aged 17–20 years, they completed a questionnaire, which included questions about asthma and allergy symptoms, asthma and allergy diagnoses, medication and current smoking.17 In addition, all the participants performed daily peak expiratory flow (PEF) measurements at home for two weeks before the study visit. The criteria for abnormal PEF were daily variability in PEF ≥ 20% or a bronchodilator response ≥ 15% at least twice during this two week period.22 A physician interviewed and examined all the participants and checked the questionnaire and confirmed the responses with the participants.17
Current asthma was defined as the presence of a previous asthma diagnosis, together with symptoms suggestive of asthma during the last 12 months. These symptoms included recurrent wheezing, a prolonged cough, a chronic night cough or continuous use of inhaled corticosteroids.17 In addition, participants who presented with abnormal home PEF monitoring results and reported asthma-presumptive symptoms and/or repeated use of bronchodilators were considered to have current asthma.17 Current asthma was present in 26 (53%) of the 49 participants who attended the follow-up visit in 2010 (Fig S1).
During the follow-up visit, SPTs for the following allergens were performed: dog, cat, horse and cow dander; birch, common alder, Timothy grass and mugwort pollens; and three types of common dust mites.17 The presence of a positive SPT result for at least one allergen was defined as current atopic sensitization. Current allergy was defined as the presence of atopic sensitization and either atopic dermatitis, allergic conjunctivitis or allergic rhinitis.