Patients with single vs. multiple food allergies may have different phenotypes

Patients with multiple food allergies had higher rates of comorbidities, such as asthma and atopic dermatitis, and they underwent more diagnostic testing, according to study results.

These results, presented at the American College of Allergy, Asthma & Immunology Annual Scientific Meeting, suggest patients with single and multiple food allergies probably represent different phenotypes that merit examination, according to the researchers.

Noting that IgE-mediated food allergies present risks for severe reactions, the researchers acknowledged that patients and caregivers may experience a large psychosocial burden and that different clinical characteristics between patients with single or multiple food allergies may influence care.

Thomas B. Casale, MD, professor of internal medicine and pediatrics and chief of clinical and translational research in the division of allergy and immunology at University of South Florida Morsani College of Medicine, and colleagues compared the self-reported clinical characteristics of these different patient populations using the Food Allergy and Research Education (FARE) Patient Registry Database, which includes more than 13,000 patients aged younger than 1 year to older than 80 years as well as more than 200 different allergens they reported experiencing.

The FARE Patient Registry Database gathers data via online surveys of patients and caregivers. Participants are primarily diagnosed through skin scratch or skin prick tests and IgE antibody testing, with few reporting use of food diaries, food elimination reports or oral food challenges.

Of the 5,593 patients in the FARE Patient Registry Database selected for the study, 18% (n = 995; mean age at diagnosis, 9.5 years; standard deviation, 15.37 years; 60.9% female; 81.3% white) reported a single food allergy, and 82% (n = 4,598; mean age at diagnosis, 7.9 years; standard deviation, 14.48 years; 55.2% female; 77.7% white) had multiple food allergies. In both groups, the most common allergens were peanuts, tree nuts, milk and egg.

“Most patients were diagnosed when they were young, [at a] mean age of about 8 [years], and patients were mostly white and fairly evenly split by sex with a slight increase in the female gender,” Casale said during his presentation.

Also, most patients had experienced their food allergies for many years, with a mean duration of 13.9 years.

Approximately one-third of the patients had a close relative with food allergies (single-allergy patients, 28.6%; multiple-allergy patients, 38.2%).

“The top three comorbidities for both groups were atopic dermatitis, asthma and allergic rhinitis, and they were the same in both groups,” Casale said.

Multiple-allergy patients had higher prevalence of all three comorbidities: atopic dermatitis (52% of multiple-allergy patients vs. 33% of single-allergy patients), asthma (49% vs. 32%) and chronic rhinitis (42% vs. 28%).

Most patients in the FARE Patient Registry were diagnosed by allergists/immunologists, including 51.6% of single-allergy patients and 52.5% of multiple-allergy patients, whereas pediatricians diagnosed 20.8% of the single-food allergy patients and 22.9% of the multiple-allergy patients.

Additionally, 64% of single-allergy patients and 73% of multiple-allergy patients had skin-prick testing, and 56% of single-allergy patients and 63% of multiple-allergy patients had IgE-antibody testing. Patients with multiple allergies more frequently used food diaries and food elimination diets than patients with single allergies as well.

“Compared with patients with only a single food allergy, patients with multiple food allergies had higher rates of comorbidities and more diagnostic testing,” said Casale. “These findings highlight that multiple food allergies likely represent a distinct phenotype from single food allergy and deserves further evaluation, especially exploring possible mechanisms.”