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.