Factors predicting the persistence of asthma insights from the Tucson children's respiratory study

The Tucson Children's Respiratory Study (TCRS) is a longitudinal, epidemiology study of respiratory health, which enrolled a birth cohort of over 1200 children from 1980 to 1984. Over 800 of these children were still being followed at adolescence allowing the characterization of several distinct wheezing phenotypes throughout childhood, as well as, those risk factors associated with the development of asthma and its persistence. Evaluating the persistence of asthma is a complex issue. There are several distinct wheezing phenotypes in childhood, which vary in prevalence and course with age. The challenge here is that the phenotypes of wheezing illness change with age; i.e. in infancy most children with wheezing illnesses are transient wheezers who will cease wheezing by age six. In contrast, by age six most children with wheeze have either persisted since infancy without apparent remission or have late onset wheeze. Both of these groups have increased rates of atopy representing dysregulated immune systems. Although its prevalence decreases substantively by early adolescence, non-atopic wheeze continues in a relevant proportion of school age children. Further, although the majority of adolescents with asthma have developed wheeze by age six, there are some who first present with asthma after this age. Thus, as children age, the meaning of wheezing transitions from most likely not being asthma in the first 3:years to most likely being asthma by late adolescence. This article will review the progression of wheezing from infancy through early adolescence and will address both changes in phenotypes as well as risk factors for both persistent and incident asthma in childhood.