Data collected in preschool and school age
At the follow-up visit one year after the index episode requiring hospitalization, asthma was diagnosed if at least three episodes of physician-confirmed wheezing during the preceding year were reported.14 In 1995, at a median age of 4.0 years, asthma was defined as the presence of a previous asthma diagnosis and at least one reported physician-diagnosed wheezing episode during the preceding year or reported use of maintenance medication for asthma.15 In 1999 and 2004, at median ages of 7.2 and 12.3 years, respectively, asthma was diagnosed if continuous maintenance medication for asthma, or repeated wheezing episodes and/or a prolonged cough apart from the infection during the preceding 12 months were reported, and the result of an exercise challenge test was positive.12,16