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Large US study confirms 'allergic march' in children

Eczema in babies could be an indicator that they will go on to develop more allergies, say researchers, after a large study confirmed that the development of allergies in children can follow a predictable path, giving clues about what’s to come.

The findings, in the journal Paediatrics, describe what’s known as the “allergic march” – a pattern that describes how allergies tend to develop and progress in children, beginning in infancy until the age of three.

NBC News reports that the experts, who analysed medical records data collected between 1999 and 2020 from more than 200 000 children, found that they tended to be first diagnosed with eczema, (atopic dermatitis), at four months, on average.

Next came diagnoses of food allergies with symptoms ranging from hives to anaphylaxis, a life-threatening allergic reaction that affects the whole body and can cause the airways to swell and close, and asthma, both at around 13-months-old.

At 26 months, the study found, children developed allergic rhinitis, or hay fever. In rare cases, they might go on to develop a fifth allergy, called eosinophilic esophagitis, by the age of about 35 months.

Dr Stanislaw Gabryszewski, a fellow in the Division of Allergy and Immunology at Children’s Hospital of Philadelphia who led the study, said the “allergic march” doesn’t mean every child who has eczema will develop every allergy described.

“Each child is different. Some may have one, others may have a couple, others may have all of them,” he said.

About one in five children has one of these types of allergies, making them one of the most common chronic illnesses in youngsters.

Just more than 13% have at least two types of allergic conditions, the researchers said.

The findings are helpful for both parents and physicians, who can monitor children who develop eczema early in life more closely for other allergies later on.

“Eczema early in life is the number one risk factor for developing allergies later in life, far more than family history,” said Dr Ruchi Gupta, founding director of the Centre for Food Allergy and Asthma Research at Northwestern University and Lurie Children’s Hospital of Chicago, who was not involved in the study.

The medical community has long recognised the allergic march, but the new research is the largest study to confirm the pattern.

“This study adds another layer of evidence that allergic diseases start early in life, and there is a progression of allergic disease that can occur together so that one child may have multiple allergic conditions,” said Dr Sharon Chinthrajah, an immunologist at Stanford University School of Medicine who was not involved in the research.

She added that sometimes the earlier allergic conditions will go away, and the child will just be left with a food allergy, for example, but other times the allergies are cumulative, leaving children with multiple types of allergies. For some, certain allergies will come and go, Chinthrajah said.

Food allergies were less common than previous research has found, affecting about 4% of the kids in the study, about half the amount seen in studies where people self-report their allergies.

The most common food allergies were peanuts, eggs and shellfish. Patients with respiratory allergies like asthma and allergic rhinitis usually had both of those conditions, in addition to other allergic conditions.

The study also found that eosinophilic oesophagitis – a rare type of food allergy that causes inflammation in the oesophagus – affects a larger proportion of non-white children than previously thought. About 40% of children who had the condition were not white. Overall, this allergy was very rare, seen in just 0.1% of them.

Better understanding how allergies commonly develop could lead to treatments that could halt the progression, or stop allergies from developing altogether.

If eczema could be prevented, “can we prevent food allergies, environmental allergies and can we prevent asthma?” Gupta asked. “We don’t know yet, but research is being done.”

Chinthrajah agreed. “Where it’s our job as researchers is to identify how do we intervene early and with those interventions, how do we influence not one of the five allergic diseases but many,” she said.

That research will need to untangle the link between environmental factors, including climate change, which is making seasonal allergies worse, and genetics.

“Ultimately it’s the interplay of the two that will dictate which children develop allergies and if they do, how severe they will be,” Gabryszewski said.

Study details

Patterns in the Development of Paediatric Allergy

Stanislaw Gabryszewski, Jesse Dudley, Di Shu, Jennifer Faerber, Robert Grundmeier, Alexander Fiks, David Hill.

Published in Pediatrics on 25 July 2023

Objectives
Describe clinical and epidemiologic patterns of paediatric allergy using longitudinal electronic health records (EHRs) from a multistate consortium of US practices.

Methods
Using the multistate Comparative Effectiveness Research through Collaborative Electronic Reporting EHR database, we defined a cohort of 218 485 children (0–18 years) who were observed for ≥5 years between 1999 and 2020. Children with atopic dermatitis (AD), immunoglobulin E–mediated food allergy (IgE-FA), asthma, allergic rhinitis (AR), and eosinophilic esophagitis (EoE) were identified using a combination of diagnosis codes and medication prescriptions. We determined age at diagnosis, cumulative incidence, and allergic comorbidity.

Results
Allergic disease cumulative (and peak age of) incidence was 10.3% (4 months) for AD, 4.0% (13 months) for IgE-FA, 20.1% (13 months) for asthma, 19.7% (26 months) for AR, and 0.11% (35 months) for EoE. The most diagnosed IgE-FAs were peanut (1.9%), egg (0.8%), and shellfish (0.6%). A total of 13.4% of children had ≥2 allergic conditions, and respiratory allergies (ie, asthma, AR) were commonly comorbid with each other, and with other allergic conditions.

Conclusions
We detail paediatric allergy patterns using longitudinal, health care provider-based data from EHR systems across multiple US states and varied paediatric practice types. Our results support the population-level allergic march progression and indicate high rates of comorbidity among children with food and respiratory allergies.

 

Pediatrics article – Patterns in the Development of Pediatric Allergy (Open access)

 

NBC News article – Eczema to hay fever: The ‘allergic march’ shows how allergies can progress in kids (Open access)

 

See more from MedicalBrief archives:

 

Breastfeeding and risks of allergies and asthma

 

Approval for first medical Tx for children with peanut allergies in 2019

 

Milk allergy guidelines may cause over-diagnosis in babies and children

 

 

 

 

 

 

 

 

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