2.1.1 Evidence from the lab linking allergic inflammation to
increased risk of chronic rhinosinusitis in children.
All studies included in a qualitative analysis support a specific link
between CRS and AR in children (Table III). Chawes(45)studied nasal eosinophilia and nasal airway patency (assessed by
acoustic rhinometry) in children with AR, non-allergic rhinitis and
healthy controls. Nasal eosinophilia and irreversible nasal airway
obstruction were significantly associated with AR, whilst there was no
such association with non-allergic rhinitis. The authors suggested that
chronic inflammation and structural remodeling of the sino-nasal mucosa
may occur in allergic children even at 6 years of age.
Some authors suggested that allergic sino-nasal inflammation may support
bacterial infection. Blair et al.(46) in an animal
model showed that allergic inflammatory reaction may obstruct sinus
drainage encouraging bacterial infection into the maxillary sinus. Shin
et al.(47) demonstrated that total IgE, total
eosinophil count, and serum eosinophil cationic protein levels were
significantly higher in CRS children whose symptoms and radiologic
abnormalities did not resolve after 12 weeks despite appropriate
antibiotic therapy (non-responder) compared with responders and healthy
controls. Moreover, AR in children may affect the efficiency of
mucociliary clearance, which is one of the most important protective
functions of the respiratory epithelium. Deterioration of muco-ciliary
system appears to be related to more severe rhinitis with a higher
intensity of local nasal inflammation, reflected in nasal smear
eosinophilia(48).
Brożek-Mądry and co-workers(49) evaluated the relation
between bacterial strains and cytological examination of nasal mucosa in
children with CRS; they found that the most common strains of bacteria
observed in CRS (Hemophilus influenzae, Moraxella catarrhalis, and
Staphylococcus aureus) were associated with a higher prevalence of atopy
and percentage of eosinophils in cytology. It must be noted that S.
aureus enterotoxins are able to induce increased severity of the
disease, amplifying eosinophilic inflammation in atopic
patients(50).
Clinical evidence linking allergic inflammation to increased
risk of chronic rhinosinusitis.
The association between allergy and CRS in adults has been discussed for
years and a strong association has been observed with particular
subtypes of CRS with nasal polyps (wNP), such as central compartment
atopic disease and allergic fungal rhinosinusitis(51,52). Manuscripts on pediatric CRS are less common
predominantly because of ethical issues regarding administration of
X-rays in the pediatric population. The publications included in the
qualitative analyses are summarized in Table IV. Conclusions of the
studies included in the qualitative analyses were not unanimously
linking allergy to chronic rhinosinusitis.
Several manuscripts seem to support a positive clinical association
between AR and CRS, describing a prevalence varying between 27% and
59% of patients(53,54,55). Brietzke et
al.(56) in an expert panel consensus, suggested that
there is a clinically-relevant association between AR and pediatric CRS,
particularly in older children. Sedaghat et al.(57),
analyzing a large series of 4044 pediatric cases, observed that AR is
one of the most prevalent comorbidity observed in children with CRS
(26.9%) even though a comparison with control group was not provided.
Choi et al.(34) showed that age, atopy, AR, and asthma
may be predisposing factors for pediatric CRS and recurrent RS. The
authors proposed that specific evaluation for allergic diseases should
be considered when managing chronic or recurrent RS. More recently,
Anamika et al.(58) demonstrated a positive skin
prick-test in 53% of the cases in a cohort of 110 children with CRS;
moreover, those with atopy had higher mean Lund-Mackay endoscopic score
and Sinus and Nasal Quality of Life Survey score than non-atopic
patients.
Huang et al.(59) attempted discrimination among
different allergies and reported that mold allergy represents a
significant risk factor for development of sinusitis, compared to
non-mold allergy, in a case series of 413 children followed for 5 years.
These data suggest that perennial allergy may be a stronger risk factor
for CRS compared to seasonal allergy.
On the other hand, some studies suggested a lack of correlation between
allergic disease and pediatric CRS. Leo et al.(60), in
a report on 351 children affected by CRS, demonstrated that the
prevalence of sensitization to aeroallergens was comparable to that of
the general pediatric population. No clinical evidence could account for
a higher rate of nasal congestion, nor a harsher clinical course, in
allergic children(61). Sedaghat et
al.(53, 62) observed that pediatric patients with AR
and CRS seem to have the same aeroallergen sensitivity profile compared
to the general pediatric population with AR. Furthermore, the authors
did not find a positive association between the number of aeroallergen
sensitivities or the presence of atopic comorbidities with the
subsequent development of CRS, suggesting that the severity of atopy
alone may not be positively predictive of CRS development. These
articles were not included in the qualitative analyses due to the type
of article.