Allergic Atopy Testing Alone Misdiagnoses Many

The use of a nasal allergen challenge (NAC) increases the diagnostic accuracy of clinical algorithms for rhinitis in children and adolescents with a history of chronic rhinitis, according to research published in Pediatric Allergy and Immunology. 

Researchers analyzed the clinical characteristics of rhinitis phenotypes in a large group of children and adolescents in an effort to both generate a clinical predictive model for local allergic rhinitis (LAR) and propose a diagnostic algorithm for pediatric rhinitis. The investigation prospectively recruited participants between the ages of 5 and 18 years with a 2-year or longer history of chronic rhinitis between January 2017 and December 2019. 

In addition to the collection of demographic and clinical data, skin-prick tests were performed for all relevant aeroallergens. A fluoroenzyme immunosorbent assay was used to determine serum allergen-specific immunoglobulin E (sIgE); the positivity cutoff was 0.35 kUA/l or greater. Allergy was evaluated via NAC with a single allergen per session atopic individuals and multiple allergens per session in nonatopic patients. Tests were positive if a 30% or greater increase in total visual analog scale, and a bilateral 30% or more decrease in the total sum of acoustic rhinometry compared with baseline, were noted. 

The total cohort included 173 patients who signed informed consent to participate. Mean age was 15.1±2.2 years and 60.1% of patients were women. Mean age at onset of rhinitis was 10.0±4.0 years. 

Within the cohort, 58.4% of patients demonstrated at least 1 positive skin-prick test and were classified as atopic. Six of these patients demonstrated negative serum sIgE results; conversely, 41.6% of participants were negative for both tests and classified as nonatopic. Atopic participants were both polyatopic (80.2%) and monoatopic (19.8%). 

Positive results of nasal allergen challenges were found in 82.1% of patients, classified as allergic individuals; the remaining 17.9% of participants were nonallergic. The primary allergens associated with positive nasal allergen challenges were Olea europaea pollen and Dermatophagoides pteronyssinus. 

Patients who were allergic had symptoms including nasal itching, sneezing, conjunctivitis, and atopic dermatitis “significantly more often than nonallergic individuals.” Exposure to house dust, vegetation, and furry animals were also triggers for rhinitis significantly more frequently than people who were nonallergic. 

Overall, 45.7%, 24.9%, and 11.6% of participants fulfilled the diagnostic criteria for allergic rhinitis, local allergic rhinitis, and dual allergic rhinitis, respectively. No significant difference in allergic phenotypes were found based on clinical or demographic parameters. Patients with allergic rhinitis reported an earlier onset of conjunctivitis (9.4±4.2 vs 12.5±2.2; P =.008), higher prevalence of seasonal allergy symptoms (25.3% vs 3.2%; P =.008), nasal itching (69.6% vs 25%; P <.001), sneezing (81% vs 45.2%; P <.001), and conjunctivitis (59.6% vs 22.6%; P <.001) compared with people with nonallergic rhinitis. 

A multivariate backward logistic regression model was used to facilitate LAR diagnosis in nonatopic patients. Four parameters — presence of moderate to severe nasal symptoms, nasal symptoms triggered by exposure to house dust, vegetation, and irritant smells — were used to generate the model. Based on these results, the researchers suggest conducting NAC in individuals ≥5 years of age who experience moderate to severe persistent rhinitis and negative or discrepant skin-prick challenge test results. 

“Our study constitutes the first systematic analysis of atopy and allergy in children and adolescents,” the research shows. “Our study demonstrates that [dual allergic rhinitis] and [local allergic rhinitis] are relevant differential diagnosis in pediatric rhinitis…emphasizing the need to implement [a nasal allergen challenge] in the clinical algorithms of rhinitis during childhood.” 

Reference

Prieto A, Rondon C, Eguiluz-Gracia I, et al. Systematic evaluation of allergic phenotypes of rhinitis in children and adolescents. Pediatr Allergy Immunol. Published online February 18, 2021. doi:10.1111/pai.13474