A new study suggests that children with allergies, such as eczema and hay fever, are more likely to develop other conditions in the future.
The study was published in Pediatrics and examined the electronic medical records for nearly 220,000 US children who were screened from 1999 to 2020. The findings provide evidence of a trend known as the allergic march. This is a natural progression in allergy-related illnesses from childhood to adulthood.
The study found that if a child has been diagnosed with one type of allergy, the likelihood of them developing another is higher than in the general population. Dr. David Hill is a pediatric allergist at the University of Pennsylvania, and is one of the authors.
The first to appear is atopic dermatitis (or eczema): its telltale rashes, dry patches, and onset usually occurs around 4 months. Around 13 months, the study discovered that anaphylactic allergies to food and asthma were at their peak in children. Asthma affected over one in five of these kids.
Researchers found that 19.7% of children aged 26 months or older had hay fever. Some kids will develop eosinophilic Esophagitis by 35 months. This is a rare allergy that causes inflammation of the esophagus.
Hill stated that this is the first study to be done using patient health data, which shows the allergy march on a nationwide level.
According to the US Centers for Disease Control and Prevention (CDC), more than one in four children suffer from eczema. Allergic reactions include rashes and congestion.
In severe cases they can lead to life-threatening conditions such as anaphylaxis. As chronic conditions, these can have a long-lasting impact on the quality of life for children.
Hill stated that these conditions have a significant impact on children's lives. Children with allergies are likely to have lower grades and miss more school. They are more prone to anxiety. Eating disorders can be caused by food allergies.
Most large-scale allergy research relies on surveys sent to parents. Hill says that this approach can lead to errors. Parents may not know what allergies their child has, and could mistake lactose tolerance for an allergy.
Hill suggested that pulling data from the records kept by healthcare providers could improve accuracy. Hill said that the new study found that food allergies among children are half as common as previously reported. He attributes this discrepancy to errors in previous survey-based studies.
According to Dr. Jonathan Bernstein, the president of the American Academy of Allergy, Asthma and Immunology, studies such as Hill's also aren't flawless. It is possible that there are still errors and variations in the way physicians classify their patients.
According to a new report, the top three food allergies diagnosed in children were shellfish, peanuts and eggs. Over 13% of children had more than one allergy, also known as a "comorbidity".
About half of asthmatics also have food allergies.
Hill was most interested in the findings of the study on eosinophilic Esophagitis (EoE), a lesser-understood allergy condition that is a relatively new addition to the allergen march sequence.
The study showed that 40 percent of children with EoE are not white. A disproportionate number were Black children with asthma and eczema.
Black children are also more likely than other racial kids to suffer from food allergies and eczema, according to CDC research. The CDC and both the new study have found that Hispanic kids are consistently low in food allergies.
Bernstein believes that early diagnosis and intervention are key to reducing the risk of allergy. Early allergic conditions like eczema involve disruption of the epithelial layer - the outermost skin layer - allowing allergens trigger an immune reaction.
Early diagnosis and treatment of eczema to restore the skin barrier can reduce the risk of allergies further down the allergic march.
Bernstein also highlighted important steps that can help a child develop their internal microbiome, such as breastfeeding and minimizing antibiotic use for infants.
He said that everyone is born with an allergy predilection. It's our exposures after birth, and even in utero that can determine if we continue to develop an allergic phenotype.