The Majority of Children Sensitized Before School-Age Develop Allergic Disease Before Adulthood: A Longitudinal Population-Based Study

• Published in: The Journal of Allergy and Clinical Immunology: In Practice
• Main Authors: Bunne, Joakim, Hedman, Linnea, Perzanowski, Matthew, Bjerg, Anders, Winberg, Anna, Andersson, Martin, Lundbäck, Bo, Platts-Mills, Thomas, Rönmark, Eva
• Format: Article in Journal/Newspaper
• Language: English
• Published: Umeå universitet, Avdelningen för hållbar hälsa 2022
• Subjects: Allergic sensitization; Asthma; Cohort study; Longitudinal study; Rhinitis; Respiratory Medicine and Allergy; Lungmedicin och allergi; Immunology in the medical area; Immunologi inom det medicinska området; Northern Sweden
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-190983; https://doi.org/10.1016/j.jaip.2021.10.023

Background: Allergic sensitization increases the risk of asthma and allergic rhinitis, but the impact of age at onset of sensitization is less studied. Objective: To examine the cumulative incidence of asthma and rhinitis up to age 19 years in relation to age at onset of sensitization to airborne allergens. Method: All children in grade 1 and 2 (median age, 8 years) in 2 municipalities in Northern Sweden were invited to undergo skin prick tests and answer a questionnaire about allergic diseases, and 88% participated. At ages 12 and 19 years, the protocol was repeated, and 1510 individuals participated in all 3 examinations. Specific IgE data were collected in a random sample at age 19 years (n = 770). Onset of sensitization was defined: 8 years or less, 8 to 12 years, 12 to 19 years, and never sensitized. Adjusted Poisson regression was used to calculate risk ratios (RRs). Results: At 19 years, those sensitized at 8 years of age or earlier had the highest risk of asthma (RR, 4.68; 95% CI, 3.15-6.97) and rhinitis (RR, 22.3; 95% CI, 13.3-37.6), and 84% had developed either asthma or rhinitis. The combination of sensitization at age 8 years or earlier and family history of allergic diseases rendered high risks for asthma (RR, 10.6; 95% CI, 6.71-16.7) and rhinitis (RR, 36.3; 95% CI, 18.9-69.7). Individuals sensitized at age 8 years or earlier showed significantly highest level of sensitization, as judged by number of positive skin test results and titers of specific IgE. Conclusions: Most individuals with sensitization at age 8 years or earlier developed asthma or rhinitis before young adulthood. The high level of sensitization in those sensitized early contributes to the high incidence of allergic airway conditions.