Bronchial asthma and hyperreactivity after early childhood bronchiolitis or pneumonia. An 8-year follow-up study.

Objective: To determine the infantile risk factors and long-term outcome up to 8 to 10 years of age for bronchial asthma and hyperreactivity in children with early-childhood bronchiolitis or pneumonia.

Design: Prospective follow-up of three groups of children.

Setting: University hospital providing primary hospital care and outpatient consultations for all pediatric patients in a defined area.

Interventions: None.

Patients: The study groups consisted of 62 children with early-childhood bronchiolitis, 29 children with early-childhood pneumonia with no wheezing, and 52 control children.

Methods: Infantile risk factors were prospectively registered until 2 years of age. Clinical examination, performed 7 to 8 years later, included recording of atopic and asthmatic symptoms from the preceding 12 months. The methacholine inhalation challenge test was used to assess bronchial hyperreactivity, and mean midexpiratory flow results were used to assess bronchial obstruction.

Main Results: Bronchial asthma was present in nine (15%) of the 62 children from the bronchiolitis group, compared with 7% in the pneumonia group and 2% in the control group. Bronchial hyperreactivity indicated by methacholine inhalation challenge was far more common; it was present in 62% of the bronchiolitis group and in 45% of the pneumonia group. Both groups differed significantly from the control group. Decreased mean midexpiratory flow values were observed in 29% and 21% of the bronchiolitis and pneumonia groups, respectively. All 10 asthmatic patients had bronchial hyperreactivity, but only 20% of hyperreactive children had asthma. An analysis of infantile risk factors disclosed only one, an early onset of wheezing, with a significant effect on bronchial hyperreactivity at school age. Elevated IgE values measured during infancy were associated with the development of clinical asthma.

Conclusions: The risk of bronchial asthma was increased after infantile bronchiolitis. Moreover, bronchial hyperreactivity was increased after both infantile bronchiolitis and pneumonia. Methacholine inhalation challenge was a sensitive but nonspecific test for diagnosing bronchial asthma. Both bronchiolitis and pneumonia resulting in hospitalization in early childhood distinguish a group of children with an increased risk for long-term lung function abnormalities and pulmonary illnesses.