CAN A CHILD OUTGROW ASTHMA?
The natural history of asthma in children younger than 5 years varies.6 Two general patterns of illness include the remission of symptoms during preschool years and the persistence of symptoms throughout childhood. The Tucson Children's Respiratory Study followed children from birth and found that of the group who had wheezing before age 3 years, 60% would report no wheezing episodes at 6 years of age.12 These children, who were called transient infant wheezers,13,14 did not have a family or personal history of atopy, had symptoms only during the first 3 years of life,12 and had diminished lung function from birth.12
The remaining 40% of the children who continued to wheeze into the school-aged years consisted of persistent nonatopic wheezers and, mostly, persistent atopic wheezers.13 Children with nonatopic wheezing did not have a family or personal history of atopy, but unlike the transient wheezers, their symptoms continued beyond 6 years of age but diminished in preadolescence.12,13 Children with the persistent atopic wheezing phenotype had atopy and a family history of asthma. These children continued to wheeze throughout the schoolaged years, often without associated viral infections, and represented the usual phenotype of childhood asthma in the 5- to 11-year age-group.
The persistence of asthma in a given child cannot be definitively predicted. 6 However, the Asthma Predictive Index (API) was developed to allow one to assess the likelihood that a child with frequent wheezing in the first 3 years of life will experience persistent asthma6,13,15 so that the child can be monitored and appropriate treatment started. Children with a positive API have a parental history of asthma or physician-diagnosed atopic dermatitis or 2 of the following: physician-diagnosed allergic rhinitis, wheezing apart from colds, or blood eosinophilia of 4% or higher.14
A retrospective analysis of 1246 patients from the Tucson Children's Respiratory Study showed that the API had a specificity of 97.4%, which is the likelihood that the schoolchildren without asthma from the original cohort would, when looking back at their histories, have had a negative API in their infancy.14,15 The study also demonstrated a positive predictive value of 76.6%, which is the probability that infants with a positive API would have had active asthma from ages 6 to 13 years, and a negative predictive value of 68.3%, which is the probability that infants with a negative API would not have experienced asthma at school age. In other words, the API was unable to correctly predict approximately 23% of persistent wheezers and 30% of transient wheezers. 14 Nonetheless, the API is currently the only available guide to assist in predicting which infants with frequent wheezing are likely to develop persistent asthma during their school years.14 Additional ongoing research is focusing on furthering phenotype- based asthma classification and individualizing treatments.16