CONCLUSIONS.
AR is a common disease in childhood in industrialized countries and it has a major impact on quality of life and health care resources. Improving the understanding of the pathophysiology of allergy and relationship with its comorbidities is important to correctly develop timed preventive measures as well as perform adequate monitoring and treatment of children with rhinitis. The correct management of allergic diseases can, in fact, decrease the inflammatory response and most likely lead to better control of comorbidities.
Our qualitative analyses demonstrated that there is clear evidence from the lab of a link between allergy and an overall impairment of mechanical and immunological defense function of nasal mucosa against viruses. Clinical studies support the hypothesis of a positive association between allergy and viral acute rhinosinusitis/URTI, and only low-quality retrospective studies reached conflicting results. Proof of this is the existence of high-quality investigations showing that anti-allergy treatments may significantly decrease the number and severity of URTI including common colds. We did not find any articles investigating specifically the link between allergy and upper airway involvement by the new coronavirus in children.
Current experimental and clinical experience does not support an etiological link between allergy and post viral rhinosinusitis, ABRS and RARS. At the moment anti-allergy treatments are not advised in these phenotypes even though well design high quality studies are required to improve our knowledge in this field reaching firm conclusions.
Despite the growing knowledge related to allergy and chronic rhinosinusitis in children, it is not yet clear whether AR may promote CRS or if they only share a common pathway of pathogenesis. Even if AR has been positively associated with CRS in several experimental and clinical studies in children, conflicting results have also been reported, probably because of discrepancies in definitions of the disease processes for both CRS and AR and allergy testing methodologies. Researchers have used a variety of techniques to document the presence of sinusitis, such as patient surveys, radiography, CT scan, rhinoscopy, and routine physical examination, and, therefore, the results may not reflect homogeneous populations. In addition, experimental studies and radiological assessment are often prevented by local ethical committees in the pediatric population, for comprehensible reasons. Furthermore, the evidence supports the hypothesis that CRS in children over the age of 13 seems to be more frequently associated with eosinophilic inflammation, whereas in younger patients with CRS neutrophilic inflammation is observed more often(10,11). We did not find investigations analyzing the impact of allergy on CRS based on age, and we believe that more data from large epidemiological studies using explicit criteria is needed.
Although there is no proof of causation, several studies suggested that evaluation of underlying allergies in CRS children is equally recommended, at least to exclude allergy as a concomitant disease and to improve control of symptoms avoiding exposure to known allergens and promoting allergy therapies. Future studies are needed to confirm that anti-allergy treatment may improve outcomes of endoscopic sinus surgery for CRS in children.
We summarized in a practical algorithm our conclusions per each phenotypes of rhinosinusitis in order to elucidate when prompt accurate diagnosis and treatment of allergy is recommended (Figure 2).