10/7/03 Factors associated with wheezing in children with bronchial hyper responsivenessSummaryBronchial hyper responsiveness (BHR), as determined by bronchoconstriction induced by inhalation of low concentrations of methacholine (Meth), is not unusual in childhood. However, only some of the children with BHR actually manifest recurrent spontaneous wheezing. Kurukulaaratchy et al of St. Mary's Hospital in the Isle of Wight, UK sequentially examined a total birth cohort (n=1456) at ages 1,2,4, and 10 years of age. BHR (bronchoconstriction induced by < 4 mg/ml of Meth) was found in 169 of the children at age 10 years. Current wheezing was present in 56% of children with BHR. Those with current wheezing had higher serum IgE levels, more frequent evidence of atopic sensitization on prick skin testing (p<0.001) and evidence of maternal asthma (p=0.01) than children of that agewith BHR but no spontaneous wheezing. Those children with BHR and wheezing at age 10 years also had a higher incidence of allergic skin test reactivity, history of maternal asthma and exposure to parental smoking when the children had been previously evaluated at age 4 years. The authors concluded that heredity, atopic reactivity (skin test, serum IgE) and environmental exposures might determine whether wheezing occurs in children with BHR. Reference J Allergy Clin Immunol 2003;112:311-6 Editor's Comments There has been increasing interest in the development of BHR in childhood. Some investigators have reported that BHR occurs relatively frequently after certain viral infections in early childhood, possibly explaining the recurrent wheezing associated with common viral infections in some children. Studies by Martinez et al and other groups indicate that the pattern of recurrent wheezing with viral infections has remitted by age 3 years in the large majority of (but not all) children. The findings described above that the factors found previously to increase the risk for wheezing continued past the age of 3-5 years (maternal asthma, allergic sensitization) is also present in the children who have BHR at age 10 years. It will be of interest to see what the course will be in those children with BHR but no apparent wheezing. A recent report suggests that BHR without wheezing persisting into adolescence is more common when the child's parents also have BHR (Chest 2003; 124:819-25). In another study, the large majority of adolescents who had "outgrown" their childhood asthma (no symptoms for ä 10 years) still had BHR.
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