Tree pollen allergen sensitization: Prevalence, risk factors, and geographic variation in the United States

Background: Many tree pollens are associated with the pathogenesis of allergic disease. Objective: Our aim was to investigate prevalence, risk factors, and geographic variation of tree pollen sensitization in the United States. Methods: Results of specific IgE testing for pollen of 31 tree species were obtained from a single United States-wide clinical laboratory by physicians' requests submitted in 2014-2023. Tree pollen sensitization data were statistically analyzed with respect to prevalence, patterns, and relationship with demographic characteristics, clinical diagnoses, and geographic regions. Results: A total of 23,932,544 specific IgE tests, originating from 3,067,173 unique patients ranging in age from 0 to 85 years were identified. Males showed higher positivity rates across all tree species and age groups. In both sexes, positivity was highest in individuals aged 10 to 19 years and in patients with atopic dermatitis and asthma. Patients living in urban areas had higher rates of sensitization than patients in rural areas. Considerable differences in top sensitizers were identified across ecoregions, even among different ecoregions present within the same US state. Rates of cosensitization to allergen pairs were generally associated with phylogenetic proximity of species. Conclusion: Factors associated with higher rates of tree pollen sensitization included being male, being a teenager, having atopic dermatitis, having asthma, and living in a specific ecologic region. Results from this study may be helpful to clinicians in counseling patients, as well as to laboratories designing geographically based allergen testing panels.