Commonality of child food allergies highlight importance of prevention and treatment
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Key takeaways:
- Among 10-year-old children in Australia, 40% had a current allergic disease and one-third of those had multiple allergies.
- Prevalence of current eczema decreased whereas current rhinitis increased.
Allergic disease affects 40% of school-aged children in Australia and 45% of food allergies among infants persist until age 10 years, according to a study published in The Journal of Allergy and Clinical Immunology: In Practice.
“Understanding how many children are affected by allergies is important for informing public health and research priorities,” Rachel L. Peters, PhD, lead author of the study and associate professor at Murdoch Children’s Research Institute, Australia, told Healio.
“It is also important to understand the impact of allergies in school-aged children to make sure schools have the strategies and resources in place, to provide a safe environment for children with allergies to learn,” she said.
During the population-based, longitudinal HealthNuts study, researchers tracked the prevalence of common allergic disease in a cohort of 5,276 children, aged 11 to 15 months at baseline, throughout childhood.
Methods
Recruitment was in Melbourne, Australia, between 2007 and 2011 with assessments at ages 6 and 10 years. Assessments included carers completing questionnaires on symptoms and doctor diagnoses of allergic conditions, as well as skin prick tests, lung function tests and oral food challenges.
SPTs tested for four common allergens: peanut, egg, sesame and either cow’s milk or shellfish. The 1,089 infants with an SPT wheal of at least 1 mm to egg, peanut or sesame were offered an OFC, with 908 (83%) participating.
At age 4 years, questionnaires were sent to caretakers, with 4,291 participating. The same protocols were used during follow-up at ages 6 and 10 years. Caretakers were again asked about the child’s allergy history.
Assessment included physical measurements, spirometry, and SPTs to 10 foods (peanut, egg white, sesame, soy, almond, cashew, hazelnut, wheat, cow’s milk and brown shrimp) and eight aeroallergens (Alternaria, Cladosporium, house dust mite, cat dander, dog dander, Bermuda grass, rye grass and birch).
Results
Out of the 5,276 participants, 4,455 (84%) and 4,065 (77%) participated at age 6 and 10 years, respectively, in the follow-up analysis. At age 6 years, 73% completed the clinical assessments, and 55% completed them at age 10 years. Overall, 2,238 children completed the clinical assessment.
The study found that children who completed the clinical assessment as well as the full questionnaire were more likely to have a family history of allergy, higher socioeconomic status and older mothers and were less likely to be exposed to tobacco than nonparticipants.
Data showed that 6.4% (95% CI, 5.6%-7.2%) of children at age 6 years and 6.3% (95% CI, 5.5%-7.2%) of children at age 10 years had an allergy to at least one food. The prevalence of food allergy remained stable between ages 6 and 10 years, but sensitivity analysis showed that there was a small decrease between those ages.
Children with a positive OFC confirmed allergy to egg, peanut or sesame at age 1 year showed a 45% probability of existing food allergy at age 10 years (n = 135 of 297), whereas 55% were not allergic to any of the measured foods.
Out of the children who did not have any food allergies at age 1 year, 1.1% developed an onset of a probable food allergy (n = 20 of 1,768) at age 10 years, and 33 of 1,580 had a new onset of a possible food allergy to the tested foods for a combined 1.6%.
Egg was the most common food allergy at age 1 year (9.5%), but the researchers said this substantially fell by age 10 years (0.6%).
Peanut was the most common food allergy at age 6 (3.1%, 95% CI, 2.6%-3.7%) and 10 years (2.9%; 95% CI, 2.5%-3.5%). The second most common food allergy at these ages was cashew (age 6 years, 2.8%; 95% CI, 2.3%-3.4%; age 10 years, 2.6%; 95% CI, 2.1%-3.1%). The third most common allergies included egg at age 6 years (1.2%; 95% CI, 0.9%-1.6%) and hazelnut at age 10 years (0.8%; 95% CI, 0.6%-1.2%).
Peanut allergy was resolved in 3.8% of participants between ages 6 and 10 years (n = 4 of 105), whereas there were no instances of cashew allergy resolution.
Aeroallergen sensitization was more common than food sensitization at both ages 6 and 10 years. At age 6 years, 36.6% (95% CI, 34.8%-38.5%) were sensitized to at least one aeroallergen, which then increased to 45.2% (95% CI, 42.9%-47.5%) by age 10 years. The two most common aeroallergens were house dust mite and rye grass.
The prevalence of asthma diagnosis was similar at ages 6 (12.1%; 95% CI, 10.9%-13.3%) and 10 years (13.1%, 95% CI, 11.9%-14.4%). Prevalence of current asthma or wheeze was slightly higher at age 6 years at 17.3% (95% CI, 16%-18.7%) compared with age 10 years (15.4%; 95% CI, 14.1%-16.8%). Allergic asthma was more common than nonallergic asthma.
“Food allergy and eczema are most common in babies, with 10% having a food allergy and one-quarter having eczema,” Peters said. “At school age, asthma and hay fever are the most common. In 10-year-old children in Melbourne, Australia, around 1 in 8 children have asthma, 1 in 8 have eczema and 1 in 4 have hay fever and 6% having a food allergy.”
The prevalence of current eczema decreased slightly from 15.3% (95% CI, 14.1%-16.7%) at age 6 years to 12.9% (95% CI, 11.7%-14.2%) at age 10 years. Compared with nonallergic eczema, allergic eczema was more prevalent.
Rhinitis was the most common allergic disease reported at age 10 years. Current rhinitis increased from 15.1% (95% CI, 13.9%-16.5%) at age 6 years to 25% (95% CI, 23.4%-26.7%) at age 10 years.
“We found that allergic diseases are common in primary-school-aged children, with nearly 40% of 6- and 10-year-olds having at least one allergic disease (food allergy, asthma, hay fever, eczema),” Peters said. “Of those with an allergy, around one-third had multiple allergic diseases.”
Study authors emphasized that these results show just how common allergies are in childhood and that more needs to be done in order to prevent them.
“These findings highlight the importance of prevention and treatment strategies for allergies, particularly for nut allergies, which tend to persist, as well as eczema, asthma and hay fever, which are very common across childhood,” Peters said.