Respiratory development of 5- to 6- year-old children experiencing a first bronchiolitis episode before age one.

BACKGROUND: The relationship between early infections due to respiratory syncytial virus (RSV), particularly bronchiolitis in infancy, and the subsequent development of asthma, bronchial hyper-responsiveness, and/or other allergic manifestations, seems increasingly certain, even if the mechanisms involved are not yet quite clear.

OBJECTIVES: The objectives of this work were to determine the prevalence of, and risk factors for, asthma and allergy in 5 to 6 year-old children who five years previously, had experienced their first episode of bronchiolitis before the age of twelve months, and to define the possible effect of the age at which the bronchiolitis occurred on the subsequent development of asthma.

METHOD: A retrospective cohort survey was conducted, based on the registers of two hospital paediatric emergency units (Unit A: the Ambroise Pare teaching hospital at Boulogne, France and unit B: the General Hospital of Cherbourg, France). The cohort comprised 5-6 years old children who had consulted or been admitted to emergency unit A or B between October 1993 and March 1994 for a first attack of bronchiolitis before the age of 12 months.

RESULTS: One hundred and twenty eight children were included in the two centres (centre A: 78; centre B: 50). A familial history of allergy was found in 92 children (71.8%). Fifty-two (40.6%) were exposed to tobacco smoke. One hundred and five children (81.2%) had been hospitalised during the first episode of bronchiolitis, but none had been placed in intensive care. Their mean age at admission was 5.1 months, and 29 children were less than three months old. Ninety seven children (75.8%) had experienced at least one episode of wheezing at some time of their life. In the twelve months before the telephone interview, 40 children (31.3%) had had at least one such episode, 47 (36.7%) an attack of asthma, 32 (25.0%) wheezing after an effort, 43 (39.4%) a dry cough at night, 52 children (40.6%) had exhibited allergic rhinitis signs, and 32 (25.0%) eczema. Among the 47 children who had experienced at least one attack of asthma during the previous twelve months, 27 (57.4%) had a history of familial asthma (p<0.04). This was the only significant relationship observed in this study with regard to risk factors for asthma. No relationship was observed between asthma or recent wheezing on the one hand, and on the others age less than three months during the first bronchiolitis episode (p=0.6), initial hospital admission (p=0.6) tobacco smoke exposure (p=0.27), sex (p=0.10) or day care management until age three (p=0.73).

DISCUSSION: This study showed a high prevalence of asthma and other allergic manifestations in children who five years previously, had experienced their first bronchiolitis episode before the age of twelve months. The only risk factor for asthma or chest wheezing identified in this study was a familial history of allergy. These data support the idea that for most children, early acute bronchiolitis, even if severe, is a transient event, with no or very few consequences in the middle or long term. Nevertheless it may be the expression of an interaction between viral infection and atopic familial predisposition leading to lasting bronchial hyper-responsiveness.