Due to its increasing prevalence and psychological and physical effects in recent decades, food allergy (FA) has become a chronic condition in the United States (US). Recent research highlights that about 10.8% of adults and 7.6% of children in the US are affected by immunoglobulin E (IgE)-mediated FA. When cases are limited to those diagnosed by a physician and those confirmed by allergy testing, the rates drop to 5.1% of adults and 4.7% of children. Contrary to this, 11.4% of children were indicated to have parent-reported FA, while 19% of adults were indicated to be allergic to at least one food.

Living with FA not only adversely affects physical health but also causes emotional distress, leads to economic burden, and negatively affects the quality of life, even for individuals who avoid exposure to triggering foods. Previous studies have also indicated that the prevalence of FA is higher among patients who have allergies to multiple foods. Patients with multi-FA have been observed to show higher rates of adverse clinical outcomes, which include the risk of anaphylaxis, the severity of food-related adverse reactions, and increased prevalence of other atopic diseases.

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Although several studies have estimated the prevalence of multi-FA in the United States, little is known about the multi-FA phenotypes and their prevalence. Understanding multi-FA can help in their prevention and treatment and help clinicians guide patients regarding disease prognosis.

A new study in the journal Annals of Allergy, Asthma & Immunology aimed to characterize the characteristics, prevalence, determinants, distribution, and psychosocial burden of multi-FA among adults and children in the US.

Study: The Epidemiology of Multi-food Allergy in the United States–A population-based study. Image Credit: Pixel-Shot / Shutterstock

About the study

The study involved the administration of a national cross-sectional FA questionnaire via telephone and web from 1st October 2015 to 31st September 2016. It was based on the probability-based AmeriSpeak Panel. Thereafter, the prevalence of IgE-mediated allergy to multiple foods was measured among adults and children in the US. The FAs were considered to be convincingly IgE-mediated (“convincing”) if the reaction to the food led to at least one symptom, which matched with the symptom list developed by the expert panel.

The food allergy independent measure (FAIM)-Adult Form and the FAIMParent-Form was used to understand the psychological burden of living with FA for adults and children, respectively. A 1-to-7-point scale was used for this assessment, where greater scores indicated a more significant psychological burden. Finally, latent class analyses (LCA) were carried out using nine indicators of FA prevalence to determine latent classes of multi-FA risk within the study population.

Study findings

The results indicated that a total of 40,443 adults and 38,408 children completed the survey. Among the 11.8% of children who reported one or more current FAs, 45% reported multiple FAs. Among the 7.6% of children who met the criteria for convincingly IgE-mediated FA, 40% reported multiple current convincingly IgE-mediated FAs. Among the 4.7% of children who reported one or more physician-diagnosed current FAs and met the convincingly IgE-mediated FA, 38% reported multiple physician-confirmed FAs. Moreover, 4.6% of children reported a single convincing FA, 1.8% reported 2-3 convincing FAs, and 1.2% reported more than three convincing FAs.

For adults, among the 19.0% of individuals who reported one or more current FAs, 48% reported multiple FAs. Among the 10.8% of adults who met the convincingly IgE-mediated FA criteria, 46% reported multiple current convincingly IgE-mediated FAs. Among the 5.1% who met one or more physician-diagnosed current FAs along with the convincingly IgE-mediated FA criteria, 42% reported multiple physician-confirmed FAs. Moreover, 5.9% of adults reported a single convincing FA, 3.1% reported 2-3 convincing FAs, and 1.7% reported more than three convincing FAs.

The results also reported that 33% of children with convincing FAs below 3 years of age reported multiple FAs, while 40% above 3 years of age reported multiple FAs. 48% of adults between 18 to 49 years with convincing FAs reported multiple FAs, which decreased to 44.5% for those between 50 to 59 years, 41.2% for those between 60 and 69 years, and 37.5% for those who were 70 years and above. Additionally, non-Hispanic White adults and children were reported to be less likely to have multiple food allergies than non-Hispanic Black adults and children.

An increase in atopic comorbidities was also observed with an increase in current convincing FAs. The number of current convincing FAs was also associated with an increase in FA-related emergency department (ED) visits, severe FA reaction, psychosocial burden, and use of epinephrine auto-injector (EAI) for treatment. Results of the latent class analysis indicated class 1 to comprise a subgroup with higher probabilities of allergies to each of the 9 FA, class 2 to comprise a subgroup with high probabilities of peanut and tree nut allergies, class 3 to comprise a subgroup with high probabilities to fin fish and shellfish allergies, and class 4 to comprise a subgroup with high probabilities to milk allergy and lesser degree egg allergy.

Children with doctor-diagnosed asthma and eczema were observed to belong to classes 1 and 2. Hispanic, non-Hispanic Asian and non-Hispanic Black children were observed to belong to class 3. Adults with allergic rhinitis were observed to primarily belong to class 2. Moreover, children born in the US were less likely to belong to a broad multi-FA class than non-native US-born children. Also, the psychosocial burden was observed to be most significant for adults and children who belonged to the broad multi-FA class, followed by those who belonged to class 2.

Therefore, the current study demonstrates that multi-FA prevalence is high among children and adults, and four major phenotypes of multi-FA occur in them. Further research is required to develop targeted therapies that will reduce the physical and psychological impacts of the disease.

Limitations

The study has certain limitations. First, misinterpretation or misdiagnosis of patients with non-food allergies that got resolved by the time the study took place. Second, the study was unable to confirm the clinically confirmed reported allergy cases.

Written by

Suchandrima Bhowmik

Suchandrima has a Bachelor of Science (B.Sc.) degree in Microbiology and a Master of Science (M.Sc.) degree in Microbiology from the University of Calcutta, India. The study of health and diseases was always very important to her. In addition to Microbiology, she also gained extensive knowledge in Biochemistry, Immunology, Medical Microbiology, Metabolism, and Biotechnology as part of her master's degree.