2/ Most sensitized children with recurrent wheeze/asthma show
comparable patterns, with a predominance of HDM sensitization
Sensitization was observed in more than half of preschoolers, confirming
that sensitization may appear early during the course of childhood
asthma. Interestingly, although preschoolers were less frequently
sensitized than school-age children, the sensitization profiles in the
two age-groups showed strong similarities. The two broader clusters
identified in each age-group were characterized by few sensitizations,
mainly to HDM, and were comparable to clusters previously described in
the U-BIOPRED cohort, although in this cohort, only 27% of preschoolers
were sensitized (10). Sensitization to HDM and multi-sensitization were
even more frequent among preschoolers with NSRW than those with SRW,
supporting our previous findings that disease severity is associated
with exposure to mold and cigarette smoke rather than atopy in this
age-group (11). The finding that patterns of sensitization to
biological sources did not clearly discriminate between children with
SA/SRW and those with milder disease confirm the results from the
U-BIOPRED cohort (10). As already mentioned, despite preschoolers being
less frequently sensitized than school-age children, the profile of
sensitization of children from the two groups showed strong
similarities, with the two broader clusters identified for children from
each group being characterized by few sensitizations, mainly to HDM.
This would suggest that, at least among sensitized children, asthma in
school-age children may share common features with wheezing in
preschoolers.
Overall, these results confirm that sensitization patterns may not be
useful biomarkers of disease severity in children when described in
terms of numbers/levels of component sensitization at a single time
point, as previously described (10). Our results reinforce the
hypothesis that more complex endotypic mechanisms, rather than simple
allergenic sensitization, underpin asthma severity during childhood.