Childhood Risk Factors and Development of Hay Fever Type Allergy

Allergic rhinitis, characterized by runny nose, is an allergic response to triggers like dust mites, pollen, etc. It affects a large proportion of the population. The present study was undertaken to investigate the link between events occurring early in life and the subsequent development of rhinitis. The results showed that females were at a lower risk of developing rhinitis in their late childhood but more in their adulthood. Children who spent their time with family, siblings, pets and farm animals, and other children in their family or at daycare were at a lower risk of rhinitis.

Allergic rhinitis or seasonal allergic runny nose, also known as hay fever, affects millions worldwide. The number of people with this long-term condition is rising. The prevalence of this condition varies across regions, ranging from 11.8 percent among Spaniards to 46 percent among Australians. With such a high prevalence, this condition claims substantial health care costs, indirect costs (like lost days at work), and affects the quality of life. Moreover, people with allergic rhinitis have a higher risk of acquiring bronchial asthma, a severely debilitating allergic breathing disease. In fact, studies have shown that children who have hay fever may be at a higher risk of getting asthma during childhood or adulthood. This study evaluated the effect of early life factors on the risk of developing rhinitis.

* This study was a part of the European Community Respiratory Health Study (ECRHS). The study was done between 1992 and 1994, and adults (1,500 men and 1,500 women) aged 20–44 years from 22 countries and 48 different centers were selected. They were subjected to clinical investigations to establish their health status.
* About 8.9 years later, these participants were reexamined at 28 centers.
* In the follow-up study, it was found that 8,486 participants had developed rhinitis. Questions related the age of onset of rhinitis and nasal allergies were asked using questionnaires.
* Statistical tests were used to predict the risk of developing rhinitis at ages less than 5, between 6 and 10, between 11 and 20, and over 21 years.

Key findings
* Of all the participants studied, the rate of new cases of rhinitis was 7 per 1,000 men per year, and 7.9 per 1,000 women per year.
* Females were less likely to get rhinitis in their later childhood but were more prone to it in their adulthood than males.
* For those participants who had siblings with a high risk of allergies, the risk of rhinitis was lower.
* The participants who spent more time with their family, siblings, or other children in daycare showed a lesser risk of rhinitis especially before they turned 5. Children who spent time with their pets or farm animals were at a lesser risk of developing rhinitis in their teenage. Mothers who smoked during pregnancy or during the initial years of their child’s life raised their children’s risk of getting rhinitis.

Next steps/Shortcomings
The authors agree that they relied on a questionnaire to diagnose rhinitis and in the process, may have missed some of the cases. In addition, they admit that the study depended upon the accuracy of recall regarding childhood exposures. This could also have skewed the results in cases of faulty recall or reporting. Future studies that follow up children into their early adulthood and evaluate the trigger factors are necessary.

Allergic rhinitis is a costly, difficult-to-treat and irksome ailment that affects large populations worldwide. It is also associated with asthma, a more serious condition. This study shows that females may be more at risk of developing rhinitis in their adulthood. The authors cite the need for future studies to understand the gender-based difference in the predisposition to rhinitis. This study also reveals that some experiences during childhood, like staying in day care or in close proximity to pets or farm animals, may help in reducing the risk of allergic rhinitis. This finding could assist in the formulation and development of newer therapies and prevention measures for allergic rhinitis or seasonal hay fever.

For More Information:
Early-life Risk Factors and Incidence of Rhinitis: Results from the European Community Respiratory Health Study—An International Population-based Cohort Study
Publication Journal: Journal of Allergy and Clinical Immunology, 2011
By Melanie Claire Matheson, PhD; Shyamali Chandrika Dharmage, MD, PhD; University of Melbourne, Australia

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