We have reinvestigated 92/101 children aged 10, who before the age of 2 years were admitted to a paediatric ward due to wheezing bronchitis. At the present time, 70% are symptom-free without medication, 20% have mild asthma, 8% moderate and 2% severe asthma. Persistent asthma correlated significantly to the presence of some other atopic disease in recent years, to early start of wheezing during infancy and to intense obstructive disease as a young child, while initial respiratory syncytial virus infection did not. A clear-cut relationship between smoking in the home in infancy and persistent asthma emerged (not visible at a preschool follow-up). The histamine challenge results correlated to the clinical picture. A normal histamine challenge was seen in 63%, mild hyperresponsiveness in 19%, moderate in 12% and pronounced hyperresponsiveness in 6%. The figures for persistent asthma and bronchial hyperresponsiveness are high compared with the prevalence of asthma in the overall population of schoolchildren.

In a prospective study 101 children aged less than 2 years (median age 10 months), were examined the first time they were admitted to a paediatric ward for asthmatic symptoms. Two-thirds were boys and 58 had parents or siblings with allergic symptoms. During winter-spring, respiratory syncytial (RS) virus was verified in 50% of children. Other viral agents were adenovirus, parainfluenza 3, coxsackie B 2, ECHO 6 and rotavirus. At the acute stage, 54% of the children displayed changes on pulmonary X-ray. The total IgE value was greater than or equal to +2 SD score units in 14 children. At reinvestigation after 3-4.5 years, when the children were aged 3.3-6.3 years, 53% were free from asthmatic symptoms; the median age for the last episode was 2 years. A total of 33% had mild asthma, 8% moderate and 6% severe asthma. The factors which correlated significantly with persistent asthma were: (1) The need for daily medication for at least 6 months. (2) A young age in conjunction with the first wheezing episode and on the first admission to a paediatric ward because of asthmatic symptoms. (3) Other past or present atopic symptoms. Heredity, tobacco smoking at home, having a furry pet, RS virus infection, or high total IgE at the time of the first admission did not correlate significantly with the persistence of asthma 3-4.5 years later. The results emphasize the good overall prognosis of wheezing in early childhood, even when the wheezing is severe enough to lead to inpatient treatment.

In children with early wheezing disorder, current allergy, bronchial hyper-responsiveness and female gender were the strongest risk factors for asthma in early adulthood, while female gender and passive smoking in infancy were independent infantile risk factors. The effects of early passive smoking persist longer than previously reported.

In subjects hospitalized due to early wheezing, pre- and post-natal smoke exposure increase the risk of asthma in early adulthood. The connection between pre-natal smoke exposure and asthma appears to be mediated via the development of bronchial hyper-responsiveness. Smoke exposure in infancy is associated with an increased risk of active smoking in early adult age, which is in turn linked to current asthma.

Aim: To study the outcome in early adulthood for children with early asthma symptoms and to analyse the factors associated with current asthma. Methods: In a prospective study, we have re‐investigated 89/101 children who were hospitalized before the age of two years due to wheezing. The children were investigated using a questionnaire and allergy and bronchial hyper‐responsiveness tests at the age of 17–20 years and compared with age‐matched controls. Results: In the cohort, 43% had had asthma symptoms in the preceding 12 months compared with 15% in the control group. The strongest risk factors for asthma were current allergy, bronchial hyper‐responsiveness and female gender. Female gender and passive smoking in infancy were independent infantile risk factors. In addition to female gender, two pathways led to current asthma: an allergic pathway from family atopy via the development of allergy and another pathway from early passive smoking via hyper‐responsiveness and active smoking. Conclusion: In children with early wheezing disorder, current allergy, bronchial hyper‐responsiveness and female gender were the strongest risk factors for asthma in early adulthood, while female gender and passive smoking in infancy were independent infantile risk factors. The effects of early passive smoking persist longer than previously reported.