Allergic Multimorbidity May Cause More Severe Allergic Disease

Mitchell H. Grayson, MD

Patients with multiple types of allergic disease and patients with frequent allergic sensitization tend to have more severe cases of allergic disease, according to new research.

A team of researchers in Brazil sought to better understand the links between allergic sensitization and allergic diseases in children and noted that it has long been thought that allergic sensitization is a marker of allergy persistence. Additionally, the presence of multiple allergic diseases has been linked with severity.

To study the question, they performed a cross-sectional study of 470 patients, aged 6 months to 18 years, looking at medical histories and measurements of specific serum Immunoglobulin E (sIgE) for whole allergens and their components.

Those patients were divided into categories: rhinitis and/or asthma (n = 111), atopic dermatitis (n = 99), food allergies (n = 95), and wheezing as infants (n = 80). The researchers found that patients with a food allergy, atopic dermatitis, or multiple allergic diseases were more likely to have more severe disease. They also found that allergic sensitization to mites was present in all 4 groups.

David A. Hill, MD, PhD, a fellow in the division of allergy and immunology at the Children’s Hospital of Philadelphia, told MD Magazine that much is already known about the topic of allergic sensitization and disease, and while he was not involved in the study, it adds detail by looking at the impact of having multiple allergic diseases.

“While there has been a fair amount of research supporting an epidemiological and pathophysiological link between the various allergic manifestations, studies of allergic co-morbidity on disease severity are comparatively lacking,” Hill said.

He added that experts are quite sure that the presence of one allergic manifestation in a patient increases their risk of developing another.

“However, we do not have a good understanding of why this is the case,” he said. “The relationship likely results from a combination of genetic, environmental, and immunologic factors.”

For pediatricians, these study results add to the body of knowledge but don’t necessarily change recommendations. Mitchell H. Grayson, MD, the director of the division of allergy and immunology at Nationwide Children’s Hospital, in Ohio, noted that allergic sensitization isn’t the same thing as allergic disease, and thus sensitization in and of itself doesn’t imply anything absent symptoms.

“In general, my recommendation to pediatricians is to not test for things to which the child is not having reactions,” said Grayson. “This has been a problem in the past with food allergy panels—children would be told they were allergic to numerous foods, only because of the test, but they actually were eating the foods without a problem, so they were sensitized and not allergic.”

Furthermore, Grayson noted that there is not much pediatricians can do to stop the so-called atopic march from atopic dermatitis to allergic rhinitis to asthma.

“As such, a child with 1 allergic disease could be considered ‘at risk’ for developing additional allergic diseases,” he said. “I do not tell pediatricians—or families—to worry about this, as right now there is little we can do to prevent the progression of the disease. We will just treat as they develop.”

Grayson, who also was not involved in the study, added a caveat: there’s some evidence that allergy shots given to patients with allergic rhinitis may prevent further progression of the march.

The study, “Allergic diseases in childhood: What allergic sensitization can teach us?” was published in The Journal of Allergy and Clinical Immunology.