Currently Viewing:
Supplements A Managed Care Perspective on Immunotherapy Treatment for Peanut Allergies
Currently Reading
Severity of Peanut Allergy and the Unmet Gaps in Care: A Call to Action
Jay A. Lieberman, MD
The Economic Impact of Peanut Allergies
H. Eric Cannon, PharmD, FAMCP
Participating Faculty
Posttest

Severity of Peanut Allergy and the Unmet Gaps in Care: A Call to Action

Jay A. Lieberman, MD
Peanut allergy is one of the most common food allergies in children, with a prevalence that has been increasing over the past several decades. The allergy is a type I, immunoglobulin E (IgE)-mediated reaction that commonly presents in childhood and can be associated with an anaphylactic response. There are many theories that attempt to explain the increasing prevalence, including dietary changes, improvements in hygiene, and intentional allergen avoidance. Diagnosis is made through a combination of a thorough patient history, peanut-specific serum-specific IgE levels, peanut skin-prick test, and, if necessary, an oral food challenge. Guidelines based on the landmark 2015 Learning Early About Peanut Allergy trial suggest that peanuts should be introduced into the diet as early as 4 to 6 months of age in infants who are at highest risk of developing peanut allergy. It is important for providers to recognize risk factors for the development of peanut allergy, identify associated clinical symptoms, and provide an accurate diagnosis of patients to effectively manage them and their families and prevent future reactions.
Am J Manag Care. 2018;24:-S0
Peanut allergies, once considered a rare occurrence, are now one of the most common food allergies among children and can be severe and potentially fatal.1 Several studies by Sicherer and colleagues have found that the prevalence of peanut allergy in children increased from 0.4% in 1997 to 0.8% in 2002 to 1.4% in 2008, as determined by a random digit telephone survey. This increase represents a 3.5-fold increase within an 11-year period.2-4 A recent survey study conducted between 2015 and 2016 estimates the prevalence of peanut allergies in children in the United States to be 2.5%, suggesting that the prevalence of peanut allergy continues to increase.5

Peanut allergies are different from other common food allergies. Egg and milk allergies are usually outgrown in most patients; however, a smaller percentage of children are expected to outgrow their peanut allergy. In a study by Ho and colleagues, 21.4% of study participants achieved a resolution of their peanut allergy by age 5 years, and Kaplan-Meier curves suggest that 34.2% will achieve resolution by age 7 years, with no additional increase in resolution beyond that age.6 A more rigorous Australian study supports these numbers, showing that 22% of 1-year-old children with challenge-proven peanut allergy outgrew their allergy by age 4 years.7

Food-related allergic reactions lead to an emergency department visit approximately once every 3 minutes in the United States.8 A retrospective cohort study conducted at 37 children’s hospitals between 2007 and 2012 found that peanuts were the allergen responsible for 37% of food allergy anaphylaxis cases and for 35% of hospital admissions due to anaphylaxis.9 An examination of a case series of deaths due to food allergies in the United States found that peanut was the single most common suspected culprit.10

Development of a peanut allergy significantly impacts not only the patient, but also the entire family. Food allergies can have a significant psychosocial effect on patients and their families, particularly considering the effect of a food allergy on a family’s daily activities and the stress of allergen avoidance.11 Another significant concern for children with food allergies is the potential for bullying or harassment. Lieberman and colleagues conducted a survey of children and their caregivers with food allergies (81.3% reported a peanut allergy) and found that 24.1% of individuals with food allergies reported being bullied, teased, or harassed because of their food allergy. When excluding children younger than 5 years, the percentage increased to 35.2%.12 A recent study by Stensgaard and colleagues found that in patients with food allergies, health-related quality of life was significantly negatively impacted by the risk of accidental food allergen ingestion, as well as by limitations placed on the child or family’s social life due to the food allergy.13

Pathophysiology

Peanut allergy is an immunoglobulin E (IgE)-mediated type I hypersensitivity reaction.14,15 In these reactions, the initial exposure to an allergenic peanut protein in a susceptible individual leads to the production of protein-specific IgE, which can then bind to high-affinity IgE receptors on mast cells and/or basophils.16 When re-exposure to the antigen occurs, the peanut allergen binds to the peanut-specific IgE on mast cells and basophils, cross linking cell-bound IgE triggering degranulation of mast cells and/or basophils, causing them to release preformed allergic mediators, such as histamine. In addition, it leads to production of other inflammatory mediators, such as prostaglandins and leukotrienes. Finally, activation of these cells induces transcription and increased production of multiple cytokines (such as interleukins IL-4 and IL-13) and chemokines, which can initiate a late-phase allergic response by attracting eosinophils, lymphocytes, and monocytes to release additional inflammatory mediators and cytokines.14,15 These combined effects lead to the clinical symptoms of allergy and sometimes anaphylaxis.16

Peanuts are legumes and are classified under the scientific name Arachis hypogaea.16 Allergenic peanut proteins can be identified due to their ability to bind to IgE in the serum of an allergic individual.17 In total, 17 peanut allergens have been identified to date, named Ara h 1 to Ara h 17, with varying degrees of allergenicity.18 Although all of these peanut proteins can bind to IgE in sensitized patients, some appear to be more clinically relevant than others. For example, using in vitro assays, Ara h 2 and Ara h 6 appear to be more potent in causing mast cell degranulation as compared with Ara h 1 and Ara h 3, whereas Ara h 8 protein sensitivity may indicate lack of clinical allergy.19,20

Peanuts usually undergo some type of thermal processing before they are consumed, depending on the region and culture.21 Commonly, peanuts are either boiled, fried, or roasted, and the choice of preparation method seems to have an impact on the prevalence of peanut allergy.21 In fact, peanut sensitization patterns differ among various geographic locations in the world.22 A lower incidence of peanut allergy has been reported in Asian countries, such as China, where peanuts are often consumed after boiling, versus the United States, where peanuts are typically roasted.23 Boiling peanuts before consumption appears to decrease the IgE binding capacity of Ara h 1, Ara h 2, and Ara h 3 versus roasting the peanuts, which is likely due to a transfer of allergens into the boiling water.23,24 In contrast, roasting peanuts appears to increase the allergenicity of peanuts and the IgE binding capacity of peanut allergens.23 The Maillard reaction, a glycosylation reaction that occurs during the dry roasting process, increases the IgE binding capacity of peanut allergens and is thought to contribute to the effect.21

Multiple theories exist to explain the rise in food allergies, including peanut allergies, over the last several decades, although none have been verified through randomized controlled trials. The hygiene hypothesis suggests that the decrease in natural microbial exposure, found especially in Western societies, shifts the body’s immune response toward IgE production and allergy when presented with a potential allergen.25 The allergen avoidance hypothesis suggests that earlier recommendations to delay introduction of allergenic foods may have led to an increase in allergy to those foods.26 The nutritional hypothesis suggests that there may be dietary factors that have affected the risk of food allergies, such as an increased incidence of low vitamin D levels in children.26 The dual allergen exposure hypothesis suggests that sensitizing skin exposure (through dust or particles in the air) can override potential tolerizing oral exposure, especially when oral exposure is delayed, and lead to food allergies.26,27

Clinical Presentation

Symptoms of peanut allergy may develop very quickly, within seconds, or up to 2 hours after ingestion of even trace amounts of peanut protein in a sensitized person (1 peanut contains approximately 300 mg of peanut protein).28 The symptoms of peanut allergy may involve several organ systems, most commonly the skin, gastrointestinal (GI) tract, respiratory system, and cardiovascular (CV) system. Skin symptoms include acute urticaria, angioedema, or a pruritic erythematous skin rash. GI symptoms may include vomiting, abdominal pain, and diarrhea.

Respiratory symptoms may include both the upper and lower airway, including wheezing, stridor, cough, dyspnea, throat tightness, rhinorrhea, and/or nasal congestion.14,28 CV symptoms, which are typically associated with anaphylaxis, include hypotension and dysrhythmia.28 The frequency of involvement of the various systems on initial peanut reaction (based on self-report) were studied by Sicherer and colleagues and are listed in Table 1.29

Patients do not typically have fatal reactions on their first known ingestion of peanuts.28 Approximately 20% to 30% of patients can also experience a biphasic, or secondary, late-phase reaction, in which allergic symptoms recur 1 to 8 hours after the initial symptoms resolve.14,28 Patients who have fatal or near-fatal reactions often have a history of asthma, food allergy, and atopy, and are more commonly adolescents or adults.28,30

The severity of an allergic reaction cannot be predicted based on the severity of past reactions or lab values.30 Severity can vary based on the amount ingested, the form of peanut ingested (raw, roasted, boiled), and co-ingestion of other foods.30 The severity may also be influenced by the age of the patient, the degree of sensitization when ingestion occurs, and how quickly the peanut is absorbed. Absorption can be influenced by factors such as whether the peanut is ingested on an empty stomach and whether exercise occurred around the time of ingestion.30

A recent large database study (N = 1070) of children with potential peanut allergy conducted by Leickly and colleagues found that 33.9% of patients diagnosed with a peanut allergy self-reported an episode of anaphylaxis on a subsequent peanut exposure, and 81.6% of these patients did not have a prior history of anaphylaxis.31 Reactions of greater severity than the initial presenting reaction occurred in 27.7% of patients; these more severe reactions were more common in children who had a skin reaction as their initial peanut reaction.31 The study also found that 33.3% of children with a history of anaphylaxis experienced anaphylaxis during a subsequent exposure. Table 2 compares the initial peanut reaction with subsequent exposure with and without anaphylaxis.31

Diagnosis

Diagnosis of peanut allergy should always begin with a thorough medical history and physical examination.30 The medical history can provide important information to estimate a prior probability of peanut allergy.32 The history should include assessment of symptoms, timing between peanut ingestion and initiation of symptoms, the type and consistency of symptoms (skin, GI, respiratory), the amount of peanut protein ingested, whether symptoms occur after eating similar foods, and any cofactors that may be related, such as exercise, alcohol use, medications, and any comorbid conditions.16,28,30,32 Critical questions to ask patients presenting with possible peanut allergy are listed in Table 3.30

 
Copyright AJMC 2006-2018 Clinical Care Targeted Communications Group, LLC. All Rights Reserved.
x
Welcome the the new and improved AJMC.com, the premier managed market network. Tell us about yourself so that we can serve you better.
Sign Up
×

Sign In

Not a member? Sign up now!