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This research highlights the close relationship between pollen-induced allergic rhinitis, sensitization, and asthma.
Children who suffer from allergic rhinitis (AR) triggered by pollen—or ‘pollen AR’—face a substantial risk of continuing the condition for a minimum of 2 decades, according to recent findings.1
Several studies the investigators of these new findings cite indicate that AR tends to increase in prevalence with age among children and that it may persist for several years, with limited information on remission. In adult individuals, remission rates have been shown to vary but can be as high as 36% over an extended period.2,3
The new long-term study examining pollen-AR was led by Magnus Lindqvist, from the Division of Immunology and Allergy’s Department of Medicine Solna at the Karolinska Institutet and Karolinska University Hospital in Stockholm, Sweden.
“The aim of this study was to investigate the natural course of pollen induced AR (pollen-AR) by prospectively following the same individuals over 20 years, including the transition from childhood into young adulthood, with respect to prevalence, persistence, remission of disease and development of asthma,” Lindqvist and colleagues wrote.
The team’s research was titled the Barn/Children Allergi/Allergy Milieu Stockholm Epidemiologic study cohort (BAMSE) and was a birth cohort study that was population-based and made up of 4,089 children who had been born in Stockholm between 1994 and 1996.
The investigators recruited children at a median age of 2 months and later tracked them through several different questionnaires related to allergies. At 4 distinct points in time—4, 8, 16, and 24 years—the team invited the subjects who had completed questionnaires for clinical follow-up assessments, including blood samples for the purposes of sIgE tests.
Their research assessed all subjects with sIgE-test results and completed questionnaire information related to symptoms of asthma, AR, and treatment with allergen immunotherapy (AIT) at the specified ages. It ended up totaling 1,137 subjects.
They subjected the blood samples to screening for allergen-specific IgE (sIgE) levels as a response to inhaled allergens using ‘Phadiatop,’ which is a combination of common inhaled allergens including grass, birch, mugwort, molds, dogs, cats, horses, and house dust mite. For their research, sera with a positive Phadiatop result—defined as sIgE levels ≥0.35 kUA/L— was further analyzed for sIgE reactivity to the airborne allergens included in the team’s screening process.
Pollen-AR was characterized by the investigators as having symptoms inclduing a runny, itchy, or congested nose, sneezing, as well eyes that itched or watered when subjects dealt with exposure to a combination of birch and/or grass pollen. It was also characterized by subjects having sIgE levels of ≥0.35kUA/L grass and/or birch.
Around 75% of the children who had reported experiencing pollen-AR by the ages of 4 or 8 were shown by the research team to have continued to have persisted in their condition until they reached 24 years of age, and about 30% of them were shown to have developed cases of asthma.
The team found that the likelihood of subjects having persistent pollen-AR was substantial even when the levels of pollen-specific IgE were found to be fairly low. They also noted that the highest rate of recovery from subjects’ pollen-AR took place between the ages of 16 - 24, with around 21.5% of them reporting remission in this time period.
Despite these findings, the investigators reported that the majority of subjects continued to be sensitized to pollen. They did add that this period also marked the point at which pollen-specific IgE levels stopped their increases, noting that the estimated annual incidence of pollen-AR decreased from 1.5% to 0.8% per year, on average.
“We can conclude that children with pollen-AR are at high risk of persistent disease for at least 20 years and that childhood up to adolescence seems to be the most dynamic period of disease progression,” they wrote. “Our findings further underline the close cross-sectional and longitudinal relationship between sensitization, AR and asthma.”