New Guidelines Issued for Food Allergies

[Guest guest]

New Guidelines Issued for Food Allergies

Medcape Medical News

by News Author: Laurie Barclay, MD; CME Author: Désirée Lie, MD,

March 16, 2006 — Guidelines created by a joint task force help

clarify the diagnosis and management of true food allergies. They

are published in the March issue of the ls of Allergy, Asthma

and Immunology.

" Food allergy, as defined for the purposes of this document, is a

condition caused by an IgE-mediated reaction to a food substance, "

write A. Chapman, MD, and colleagues from the American Academy

of Allergy, Asthma and Immunology. " Adverse reactions to foods may

also occur due to non–IgE-mediated immunologic and nonimmunologic

mechanisms.

The authors note that food allergy is an important subset of all

adverse food reactions that is often misunderstood. Because of

important new scientific findings, the evaluation and management of

food allergy have changed significantly in recent years. Potentially

fatal food allergy to peanuts and tree nuts is becoming more common

or at least more widely recognized.

" This has resulted in an increased awareness among the general

public, leading to policy changes in schools, eating establishments,

and the airline industry, " the authors write. " At the same time,

diagnostic evaluation in patients suspected of having food allergy

has become both more sophisticated and more challenging. "

The objectives of this practice parameter on food allergy include

improved understanding of food allergy by healthcare professionals,

medical and nursing students, interns, residents, fellows, managed

care executives, and administrators; establishing guidelines and

support for the practicing clinician; and improving the quality of

care for patients with food allergy. However, these guidelines are

not intended to replace clinical judgment or to establish a protocol

for all patients.

During their lifetime, about one quarter of the population will have

some sort of adverse reaction to food, especially during infancy and

early childhood. Based on the underlying pathophysiologic changes,

these adverse reactions are classified as food allergy, food

intolerance, pharmacologic reactions, food poisoning, and toxic

reactions. True food allergy is relatively uncommon, but individuals

with atopy are at greater risk, especially infants with moderate to

severe atopic dermatitis. Children who develop an IgE-mediated

allergy to one food are at increased risk of developing IgE-mediated

reactions to other foods and/or inhalants. Because the true

prevalence of food allergy is much lower than the number of adverse

reactions to food, healthcare professionals should not perpetuate

false assumptions about food allergy.

" If a patient is incorrectly diagnosed as having a reaction to a

food, unnecessary dietary restrictions may adversely affect quality

of life, nutritional status, and, in children, growth, " the authors

write. " Severely restricted diets may lead to the development of

eating disorders, especially if they are used for prolonged periods,

or may make the patient susceptible to false claims of

scientifically unproven and often costly techniques that offer no

actual benefit. In addition, unintentional exposure to foods falsely

thought to cause adverse reactions can provoke unnecessary panic and

use of medications that have potentially potent adverse effects. "

IgE-mediated food allergies may occur by sensitization through the

gastrointestinal tract, sensitization through the respiratory tract

to airborne proteins identical or homologous to those in particular

foods, or sensitization through epidermis with impaired barrier

function. Thenature and dose of antigen, host immaturity, genetic

susceptibility, rate of absorption of a dietary protein, and the

conditions of antigen processing may all affect mucosal adaptive

immunity in the gastrointestinal tract.

Molecular and immunologic techniques can help determine which

allergens or epitopes of an allergen in a particular food may be

responsible for specific clinical outcomes. Immune responses to a

particular allergen may differ based on the method of exposure and

the condition of the food.

Sensitivity to most food allergens, such as milk, wheat, and egg,

tends to resolve in late childhood, but allergies to peanut, tree

nuts, and seafood are likely to be lifelong. Peanut allergy, which

affects approximately 0.6% of the general population, is the most

common cause of fatalfood-induced anaphylaxis, especially in

adolescents with asthma. Allergies to fruits and vegetables are the

most common food allergies reported by adults, and these maydevelop

later in life because of shared homologous proteins with airborne

allergens such as pollens.

Risk factors for developing food allergy include a personal or

family history of atopy or food allergy, maternal consumption of

major food allergens during pregnancy or breast-feeding, atopic

dermatitis, and transdermal food exposure. For infants at increased

risk, breast-feeding and avoidance of highly sensitizing and/or

solid foods at a young age may help reduce this risk.

Symptoms of food allergy may be mild, develop gradually, and be

limited to the gastrointestinal tract, or they may be severe,

rapidly progressing, life-threatening anaphylactic reactions

triggered by even small amounts of food allergen. There is a strong

temporal relationship between the onset of the reaction and exposure

to a specific food or food additive, and symptoms may include skin

manifestations, gastrointestinal symptoms, respiratory symptoms,

hypotension, and laryngeal edema, occurring separately or together.

Anaphylaxis may occur in highly sensitive patients or when

triggering foods are ingested before or after exercise.

Evaluation of food allergy should begin with a detailed history

featuring a list of suspect foods, the quantity of food triggering a

reaction, the reproducibility of the reaction and its temporal

relationship to food ingestion, time elapsed between exposure and

reaction, clinical symptoms, resolution of symptoms when the suspect

food is eliminated, and duration of symptoms overall and after each

exposure. A written record of dietary intake may be helpful.

Physical examination should focus on suspected targeted organ

systems including the skin, lungs, and gastrointestinal tract, and

it should reveal or rule out alternative diagnoses to food allergy.

Atopic disorders including asthma, atopic dermatitis, and allergic

rhinitis increase the likelihood of food allergy.

Skin prick or puncture tests may be useful for screening. Commercial

food extracts from foods with stable proteins, such as peanut, milk,

egg, tree nuts, fish, and shellfish, reliably detect specific IgE

antibodies in most patients, but extracts from fruits, vegetables,

and other foods containing labile proteins are less reliable. In the

latter case, pricking the food and then the patient may be helpful.

However, skin or in vitro test results may remain positive even when

the patient's skin is no longer clinically sensitive.

Intracutaneous or intradermal skin tests are not recommended because

they are potentially dangerous, overly sensitive, and associated

with an unacceptable rate of false-positive reactions. A positive

skin test result has a positive predictive value of no greater than

50%, whereas a negative skin test has a negative predictive value of

95% or greater, virtually ruling out an IgE-mediated mechanism.

Because allergy to multiple foods is uncommon, skin testing should

be selective for suspected foods. Larger wheal-flare reactions on

prick or puncture tests and higher concentrations of food-specific

IgE measured by in vitro tests are correlated with a greater

likelihood of reaction.

In vitro tests to evaluate possible IgE-mediated reactions may be

especially valuable in patients with a history of a life-threatening

reaction to the suspected food; in those with medical conditions,

such as extensive atopic dermatitis or dermatographism that could

hinder interpretation of skin test results; in those with a

nonreactive histamine control; or in pregnant women. Patients with a

history of anaphylactic reaction and positive test results for

specific IgE antibodies usually require no further evaluation.

Other tests being investigated for their utility in diagnosing IgE-

mediated reactions to foods include atopy patch tests, hair

analysis, food specific IgG or immune complex assays, and newer

versions of the previously disproved cytotoxic tests. However,

provocation-neutralization is considered disproved as a diagnostic

method in allergy.

Challenge with a suspected food may help to determine if test

results were falsely negative or falsely positive, especially if

done in a double-blind, placebo-controlled fashion. Consultation

with an allergist-immunologist may benefit patients who have a

history of reactions to foods that could be IgE-mediated.

Managing food allergy relies primarily on avoiding exposure to foods

suspected or proven to be responsible for the patient's symptoms

based on history and appropriate tests. If this is not possible,

patients with chronic symptoms may benefit from an elimination diet.

However, patients have an increased risk of unintentional food

allergen exposure in special circumstances including schools and

restaurants. The patient and/or the patient's advocate should be

educated to read labels and to recognize that unfamiliar terms may

indicate the presence of a food allergen.

Avoiding the identified food allergen may improve the likelihood

that tolerance will develop with time, especially with cow's milk,

egg, and soy. There are currently no known oral or parenteral agents

consistently shown to prevent IgE-mediated reactions to food, and

such measures should not be relied upon. Immunotherapy to food

proteins is currently experimental. Injectable epinephrine is the

treatment of choice for an anaphylactic reaction of any cause.

" For this reason, patients who have experienced IgE-mediated

reactions to a food or their caregivers should be educated and

provided with injectable epinephrine to carry with them, " the

authors write. " Because anaphylactic reactions may be prolonged or

biphasic, it is reasonable to instruct the patient to carry more

than one epinephrine injector, to seek immediate medical care after

a reaction, and to be monitored for an appropriate period. "

Ann Allergy Asthma Immunol. 2006;96:S1-S68

# # #

Pure Air Control Services, Inc.

1-800-422-7873

[Guest guest]

great find KC, thank

you

>

> New Guidelines Issued for Food Allergies

> Medcape Medical News

> by News Author: Laurie Barclay, MD; CME Author: Désirée Lie, MD,

>

>

>

> March 16, 2006 — Guidelines created by a joint task force help

> clarify the diagnosis and management of true food allergies. They

> are published in the March issue of the ls of Allergy, Asthma

> and Immunology.

>

> " Food allergy, as defined for the purposes of this document, is a

> condition caused by an IgE-mediated reaction to a food substance, "

> write A. Chapman, MD, and colleagues from the American Academy

> of Allergy, Asthma and Immunology. " Adverse reactions to foods may

> also occur due to non–IgE-mediated immunologic and nonimmunologic

> mechanisms.

>

> The authors note that food allergy is an important subset of all

> adverse food reactions that is often misunderstood. Because of

> important new scientific findings, the evaluation and management of

> food allergy have changed significantly in recent years.

Potentially

> fatal food allergy to peanuts and tree nuts is becoming more common

> or at least more widely recognized.

>

> " This has resulted in an increased awareness among the general

> public, leading to policy changes in schools, eating

establishments,

> and the airline industry, " the authors write. " At the same time,

> diagnostic evaluation in patients suspected of having food allergy

> has become both more sophisticated and more challenging. "

>

> The objectives of this practice parameter on food allergy include

> improved understanding of food allergy by healthcare professionals,

> medical and nursing students, interns, residents, fellows, managed

> care executives, and administrators; establishing guidelines and

> support for the practicing clinician; and improving the quality of

> care for patients with food allergy. However, these guidelines are

> not intended to replace clinical judgment or to establish a

protocol

> for all patients.

>

> During their lifetime, about one quarter of the population will

have

> some sort of adverse reaction to food, especially during infancy

and

> early childhood. Based on the underlying pathophysiologic changes,

> these adverse reactions are classified as food allergy, food

> intolerance, pharmacologic reactions, food poisoning, and toxic

> reactions. True food allergy is relatively uncommon, but

individuals

> with atopy are at greater risk, especially infants with moderate to

> severe atopic dermatitis. Children who develop an IgE-mediated

> allergy to one food are at increased risk of developing IgE-

mediated

> reactions to other foods and/or inhalants. Because the true

> prevalence of food allergy is much lower than the number of adverse

> reactions to food, healthcare professionals should not perpetuate

> false assumptions about food allergy.

>

> " If a patient is incorrectly diagnosed as having a reaction to a

> food, unnecessary dietary restrictions may adversely affect quality

> of life, nutritional status, and, in children, growth, " the authors

> write. " Severely restricted diets may lead to the development of

> eating disorders, especially if they are used for prolonged

periods,

> or may make the patient susceptible to false claims of

> scientifically unproven and often costly techniques that offer no

> actual benefit. In addition, unintentional exposure to foods

falsely

> thought to cause adverse reactions can provoke unnecessary panic

and

> use of medications that have potentially potent adverse effects. "

>

> IgE-mediated food allergies may occur by sensitization through the

> gastrointestinal tract, sensitization through the respiratory tract

> to airborne proteins identical or homologous to those in particular

> foods, or sensitization through epidermis with impaired barrier

> function. Thenature and dose of antigen, host immaturity, genetic

> susceptibility, rate of absorption of a dietary protein, and the

> conditions of antigen processing may all affect mucosal adaptive

> immunity in the gastrointestinal tract.

>

> Molecular and immunologic techniques can help determine which

> allergens or epitopes of an allergen in a particular food may be

> responsible for specific clinical outcomes. Immune responses to a

> particular allergen may differ based on the method of exposure and

> the condition of the food.

>

> Sensitivity to most food allergens, such as milk, wheat, and egg,

> tends to resolve in late childhood, but allergies to peanut, tree

> nuts, and seafood are likely to be lifelong. Peanut allergy, which

> affects approximately 0.6% of the general population, is the most

> common cause of fatalfood-induced anaphylaxis, especially in

> adolescents with asthma. Allergies to fruits and vegetables are the

> most common food allergies reported by adults, and these maydevelop

> later in life because of shared homologous proteins with airborne

> allergens such as pollens.

>

> Risk factors for developing food allergy include a personal or

> family history of atopy or food allergy, maternal consumption of

> major food allergens during pregnancy or breast-feeding, atopic

> dermatitis, and transdermal food exposure. For infants at increased

> risk, breast-feeding and avoidance of highly sensitizing and/or

> solid foods at a young age may help reduce this risk.

>

> Symptoms of food allergy may be mild, develop gradually, and be

> limited to the gastrointestinal tract, or they may be severe,

> rapidly progressing, life-threatening anaphylactic reactions

> triggered by even small amounts of food allergen. There is a strong

> temporal relationship between the onset of the reaction and

exposure

> to a specific food or food additive, and symptoms may include skin

> manifestations, gastrointestinal symptoms, respiratory symptoms,

> hypotension, and laryngeal edema, occurring separately or together.

> Anaphylaxis may occur in highly sensitive patients or when

> triggering foods are ingested before or after exercise.

>

> Evaluation of food allergy should begin with a detailed history

> featuring a list of suspect foods, the quantity of food triggering

a

> reaction, the reproducibility of the reaction and its temporal

> relationship to food ingestion, time elapsed between exposure and

> reaction, clinical symptoms, resolution of symptoms when the

suspect

> food is eliminated, and duration of symptoms overall and after each

> exposure. A written record of dietary intake may be helpful.

>

> Physical examination should focus on suspected targeted organ

> systems including the skin, lungs, and gastrointestinal tract, and

> it should reveal or rule out alternative diagnoses to food allergy.

> Atopic disorders including asthma, atopic dermatitis, and allergic

> rhinitis increase the likelihood of food allergy.

>

> Skin prick or puncture tests may be useful for screening.

Commercial

> food extracts from foods with stable proteins, such as peanut,

milk,

> egg, tree nuts, fish, and shellfish, reliably detect specific IgE

> antibodies in most patients, but extracts from fruits, vegetables,

> and other foods containing labile proteins are less reliable. In

the

> latter case, pricking the food and then the patient may be helpful.

> However, skin or in vitro test results may remain positive even

when

> the patient's skin is no longer clinically sensitive.

>

> Intracutaneous or intradermal skin tests are not recommended

because

> they are potentially dangerous, overly sensitive, and associated

> with an unacceptable rate of false-positive reactions. A positive

> skin test result has a positive predictive value of no greater than

> 50%, whereas a negative skin test has a negative predictive value

of

> 95% or greater, virtually ruling out an IgE-mediated mechanism.

> Because allergy to multiple foods is uncommon, skin testing should

> be selective for suspected foods. Larger wheal-flare reactions on

> prick or puncture tests and higher concentrations of food-specific

> IgE measured by in vitro tests are correlated with a greater

> likelihood of reaction.

> In vitro tests to evaluate possible IgE-mediated reactions may be

> especially valuable in patients with a history of a life-

threatening

> reaction to the suspected food; in those with medical conditions,

> such as extensive atopic dermatitis or dermatographism that could

> hinder interpretation of skin test results; in those with a

> nonreactive histamine control; or in pregnant women. Patients with

a

> history of anaphylactic reaction and positive test results for

> specific IgE antibodies usually require no further evaluation.

>

> Other tests being investigated for their utility in diagnosing IgE-

> mediated reactions to foods include atopy patch tests, hair

> analysis, food specific IgG or immune complex assays, and newer

> versions of the previously disproved cytotoxic tests. However,

> provocation-neutralization is considered disproved as a diagnostic

> method in allergy.

>

> Challenge with a suspected food may help to determine if test

> results were falsely negative or falsely positive, especially if

> done in a double-blind, placebo-controlled fashion. Consultation

> with an allergist-immunologist may benefit patients who have a

> history of reactions to foods that could be IgE-mediated.

>

> Managing food allergy relies primarily on avoiding exposure to

foods

> suspected or proven to be responsible for the patient's symptoms

> based on history and appropriate tests. If this is not possible,

> patients with chronic symptoms may benefit from an elimination

diet.

> However, patients have an increased risk of unintentional food

> allergen exposure in special circumstances including schools and

> restaurants. The patient and/or the patient's advocate should be

> educated to read labels and to recognize that unfamiliar terms may

> indicate the presence of a food allergen.

>

> Avoiding the identified food allergen may improve the likelihood

> that tolerance will develop with time, especially with cow's milk,

> egg, and soy. There are currently no known oral or parenteral

agents

> consistently shown to prevent IgE-mediated reactions to food, and

> such measures should not be relied upon. Immunotherapy to food

> proteins is currently experimental. Injectable epinephrine is the

> treatment of choice for an anaphylactic reaction of any cause.

> " For this reason, patients who have experienced IgE-mediated

> reactions to a food or their caregivers should be educated and

> provided with injectable epinephrine to carry with them, " the

> authors write. " Because anaphylactic reactions may be prolonged or

> biphasic, it is reasonable to instruct the patient to carry more

> than one epinephrine injector, to seek immediate medical care after

> a reaction, and to be monitored for an appropriate period. "

> Ann Allergy Asthma Immunol. 2006;96:S1-S68

>

>

>

>

> # # #

>

>

> Pure Air Control Services, Inc.

>

>

> 1-800-422-7873

>