Children Face Longterm Allergic Rhinitis Risk Due to Pollen

Credit: Unsplash / Lukasz Szmigiel

Children who experience allergic rhinitis (AR) due to pollen exposure could be at a much higher risk of experiencing the condition over the next 20-plus years.

The new long-term study examining so-called pollen AR was led by investigators at the Karolinska Institutet and Karolinska University Hospital in Stockholm, Sweden. The research aimed to build on prior data showing that AR prevalence is linked to increasing age in children.

Whereas more than one-third of adults with AR are estimated to reach remission, little research has shown what that rate looks like for affected children.

“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,” investigators wrote.

The team conducted a population-based birth cohort study made up of about 4,000 children who had been born in Stockholm between 1994 and 1996.

The investigators recruited children at a median age of two months and later tracked them through several different questionnaires related to allergies. At four distinct points in time—four, eight, 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 percent of the children who had reported experiencing pollen-AR by the ages of four or eight 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 percent 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 percent to 0.8 percent 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.”

An original version of this article was published by sister site HCPLive.