Atopy phenotypes in the Childhood Asthma Prevention Study (CAPS) cohort and the relationship with allergic disease

Abstract

We have used a LCA model to define atopy phenotypes empirically. The finding of a strong association between the mixed food and inhalant sensitization class and the presence of asthma and poor asthma control at age 8 years implies that food sensitization in early life may be of greater significance for subsequent risk of asthma than previously thought.

Childhood asthma phenotypes in the twenty-first century

“…Atopy is certainly more strongly associated with persisting wheezing phenotypes than with transient viral-triggered wheezing and the classification of asthma into an atopic and non-atopic phenotype is relatively straightforward from a clinical perspective. However, this approach may be to fall into a trap of regarding atopy as a single disease entity analogous to the previous concept of asthma; several groups have now applied clustering methods to atopy and have reported discrete phenotypes that differ in their associations with asthma [18,19]. Therefore, it seems likely that multidimensional and sophisticated statistical approaches will be needed to untangle the component phenotypes of even seemingly straightforward clinical categories.…”

The hope in redefining atopy

“…The overall picture of results reported by Garden et al [1] is similar to that of Simpson et al [12], with some notable exceptions: (1) In both studies, mixed food and inhalant sensitisation was associated with the greatest risk of allergic disease and impaired lung function, but (2) there was no 'non-dust mite' group identified in the analysis of the CAPS, and the prevalence of mono-sensitisation to house dust mite was also much higher in the CAPS. It seems likely that the differences been the studies are due to population differences (MAAS is population based while CAPS is a high risk cohort) and geographic differences (levels of dust mite allergen in the Sydney based CAPS study are much higher).…”

“…This is driven by the belief that the reason for inconsistent evidence on the aetiology of these conditions is related to lack of clarity in outcome definitions. The study by Garden et al [1] published in this issue of the Journal is another important step in this process.…”

“…In this issue, Garden et al use data from the Childhood Asthma Prevention Study (CAPS) to identify distinct atopy phenotypes [1]. In a cohort of children from Sydney, Australia, with a family history of allergic disease, skin prick tests were performed at 1.5, 3, 5, and 8 years to 10 food and inhalant allergens.…”

“…Garden et al [1] achieved these results by fitting a latent class model to each child's pattern of SPT responses (up to 40 tests per child). In this instance, a latent class is represented by a series of time-specific probabilities of positive SPT.…”