Definitions
Admission symptoms were investigated at the patient’s first visit by a standardized list of questions based on the International Study of Asthma and Allergies in Childhood (ISAAC)(5) using the German questionnaire developed by Duhme et al. (1998)(6). Additional questions were used as have been previously described in detail elsewhere(7).Wheezing not associated with colds was defined as a positive response to the question: “Has your child had wheezing or whistling in their chest in the past twelve months without a cold”. Wheezing associated with colds had the same definition as the clinical evidence of a viral cold(8). Ever had wheezing was defined as a positive response to the question: “Has your child ever had wheezing or whistling in their chest at any time in the past”(5). All symptoms were reported by the children and confirmed by the parents or by a physician. Children with at least one positive answer were declared as having asthma-like symptoms.