Food Allergy
Food allergy (FA) is a common condition in early childhood, affecting up to 10% of children under 5 years. It is defined as an adverse immunologic reaction to a food protein.
Introduction
Food allergy (FA) is a common condition in early childhood, affecting up to 10% of children under 5 years. It is defined as an adverse immunologic reaction to a food protein. Many FA are IgE-mediated immediate hypersensitivity reactions, while immunologic mechanisms other than IgE also occur. These are referred to as non IgE-mediated reactions. Food intolerance does not have an immunologic mechanism.
A useful overview can be found in the recently published article: Food allergy: A review and update on epidemiology, pathogenesis, diagnosis, prevention, and management Scott H Schierer, MD and Hugh Sampson, MD. J Allergy Clin Immunol, Jan 2018. See http://www.jacionline.org/article/S0091-6749(17)31794-3/fulltext#pageBody to access the full article
Guidelines on the diagnosis and management of food allergy are available as follows:
The Irish Food Allergy Network has provided a useful summary of food allergy: http://ifan.ie/food-allergy-in-summary/summary/
Diagnosis
Diagnosis is based on clinical history, with the history of an immediate allergic reaction critical in the interpretation of skin-prick test (SPT) or serum specific IgE (ssIgE, also referred to as RAST or EAST).
The Allergy CN recommends an approach to diagnosis including testing as follows:
Allergy focussed history
The food
Most food allergic reactions are due to a small number of foods, with milk, egg, peanut, nut, sesame, fish, shellfish, kiwifruit, wheat and soy accounting for the large majority of reactions.
Timing
Most food allergic reactions come on quickly after eating a new food - 75% of milk and peanut reactions occur on first known ingestion. Onset of IgE mediated reactions is often within minutes and almost always within a couple of hours. Food allergic reactions tend to completely resolve within hours.
Signs and symptoms
IgE mediated reactions can include a variety of signs and symptoms, and no one feature is always present. Common signs and symptoms are listed on the ASCIA action plans https://www.allergy.org.au/health-professionals/ascia-plans-action- and-treatment
What to test
Allergy skin prick tests (SPT) and specific IgE (ssIgE, previously also referred to as RAST or EAST) are not screening tests. They are easiest interpreted when there is a clinical history of food allergy. Where there is a positive test but no history of food allergy, the test may indicate sensitisation rather than true allergy, and may lead to inappropriate and unnecessary food exclusion.
Sometimes anticipatory testing may be useful - e.g. many paediatricians and allergy specialists suggest testing tree nuts if a child has had a reaction to peanut, or if a child has multiple food allergies on history then testing a broader range may be needed. These decisions should be made by the specialist who sees the child in discussion with the familyConditions where food allergy testing is not indicated
If there is no history of an IgE mediated food allergic reaction (see www.allergy.org.au) then food allergy testing is not indicated. The down side to food allergy testing is that it may detect sensitisation rather than clinical allergy, and lead to inappropriate and unnecessary food avoidance. This could potentially result in loss of previous tolerance, or could increase the long term chance of developing clinical food allergy.
This applies to children with eczema where there is no history of immediate food allergic reaction. Children with eczema have an increased chance of also having food allergy, but food allergy does not cause eczema, and there is no good data that food avoidance is useful in the management of eczema.Conditions where dietitian referral is recommended
Removal of dairy +/or wheat from a child's diet can lead to a restricted diet if appropriate food substitutes are not included. This can impact micronutrient intake such as calcium and reduce overall calorie intake which can result in growth issues.
Other resources for health professionals include:
Signs and symptoms of an IgE-mediated allergic reaction:
| Cutaneous | Urticaria Angiodema Flushing/erythema Itch |
| Respiratory | Watery rhinorrhoea Sneezing Tongue swelling* Hoarseness/laryngeal oedema* Cough* Wheeze* Stridor* |
| Gastrointestinal Tract | Vomiting Abdominal pain Diarrhoea |
| Cardiovascular/general | Pallor* Dizziness* Collapse* |
*Features of anaphylaxis, defined as a severe allergic reaction with involvement of cardiovascular and/or respiratory systems.
Referral
Specialist paediatric referral and dietetic support is recommended for children with food allergy with:
Definite or possible anaphylaxis.
Allergy to cow's milk or multiple food allergies, where expert advice is needed.
Where there is uncertainty about the diagnosis or interpretation of results.
Food sensitisation on ssIgE / SPT, where supervised challenge may be necessary to clarify whether there is clinical allergy.
Allergy to foods such as peanut and nut where the risk of severe allergic reactions is higher.
Children with asthma and FA, with asthma a risk factor for severe food allergic reaction on accidental exposure.
Children whose FA persists past 5 years of age.
Management in Primary and Secondary Care
Allergen avoidance, risk management (particularly in relation to the potential for anaphylaxis), dietetic support, and follow-up are the main features of the management of food allergy. Eventual referral for specialist supervised food challenge may be necessary. Refer to the Guide to Food Challenges and Competencies for the care of a patient having a Food Challenge for more information
Patient education in all aspects is important. Patients should be provided with an Action Plan - Allergy or Anaphylaxis - signed by their doctor. These are available from the ASCIA website on:http://www.allergy.org.au/health-professionals/anaphylaxis-resources. The Paediatric Allergy Clinical Network also has more information on the management of anaphylaxis.
Refer to the Guide to Ongoing Care of children and young people with food allergy for more information.
Dietetic support is recommended for children with allergy to cow's milk. Information on the calcium needs of children with cow's milk allergy is available here, or parents/families can view the information on www.kidshealth.org.nz
Clinical Update for Dietitians: ASCIA has published a Clinical Update to complement the ASCIA food allergy e-training for dietitians. The main purpose of this document is to provide an evidence-based, 'quick reference guide' to assist dietitians in the management of patients with IgE and non-IgE mediated food allergy. The Clinical Update for Dietitians is available here:
http://www.allergy.org.au/images/stories/pospapers/ASCIA_HP_Clinical_Update_Food_Allergy_2016_dietitian_version_UPDATED.pdf
Food Challenges
Introduction and general principles
Patients with food allergy need to avoid foods as completely as necessary for as long as required, but equally one aim of food allergy management is to liberalise the diet as soon as safely possible.
The ability to undertake a safe, supervised food challenge is an important component of any paediatric allergy service.
Formal hospital challenge should be available in regional paediatric centres that provide care to children with food allergy
Food challenge indications include:
To clarify whether a food allergy has resolved
To determine whether an allergen is tolerated in modified form (eg baked egg or baked milk)
To decide whether sensitisation reflects clinical allergy
There is no New Zealand data about allergy test results and likelihood of tolerance, but there is other published data to inform probability of tolerance at challenge.
It is important to take into account family preference particularly related to the likelihood of tolerance – a 10% chance of tolerance may be sufficient for some families to want to pursue challenge, but not for others.
Current advice is that if a food is tolerated at challenge the food should then be included in the child’s diet on a regular basis, therefore
Prior to agreeing to food challenge, patients/ families need to understand the importance of, if tolerated, continued exposure to the challenge food (at least once a week) to maintain tolerance.
Red flags
Anaphylaxis
Don’t consider a food challenge if recent anaphylaxis:Within 2 years for allergens where resolution is likely
A longer wait period prior to considering challenge may be appropriate for allergens where resolution is less likely (eg peanut / nut / fish)
Previous severe reaction after small exposure.
Test results
Allergy skin prick or specific IgE test results (usually within 3 months of challenge referral) will help determine whether challenge is appropriate.
Some challenges are to determine allergy, where there is sensitisation but no prior reaction. In this instance we may accept a low probability of tolerance in order to avoid unnecessarily labelling as allergic.
Where there is known allergy a 50% chance of tolerance at challenge may be appropriate.
Published thresholds for allergy skin prick test or specific IgE may give an indication of high likelihood of allergy, where food challenge may not be appropriate:
| SPT mm in <2yr | SPT mm in >2 yr | ssIgE kUA/l in <2 yr | ssIgE kUA/l in >2 yr |
|---|---|---|---|---|
Milk | 5 | 7 | 15kUA/l | 30 |
Milk in baking | Consider* | Consider* | ||
Egg | 4 | 6 | 2 | 7 |
Egg in baking | Consider* | Consider* | ||
Peanut | 8bc | 8 | 34b | 15 |
Ara h2 |
|
| >1 | >1 |
Wheat | 10a | Consider* | Consider* | Consider* |
Soy | Consider* | Consider* | ||
Nuts | 8 | 15 | ||
Other | Consider* | Consider* | ||
ᵃChristensen 2014, ᵇPeters 2013, ᶜJohannsen 2011, ᵈNW 2008
Consider* - depending on age, tests, family preference, single versus multiple allergies etc
Conduct
Food challenge is a valuable resource. Having a locally accepted process for referral for challenge, and review of referrals to ensure appropriateness will help ensure the resource is used carefully.
All case series of paediatric food challenge include cases of anaphylaxis. There needs to be clear lines of responsibility for challenge supervision, and there must be availability of prompt medical review in the event of reaction.
Informed consent should be obtained prior to starting the challenge.
Close supervision during challenge is essential.
Nurses undertaking food challenges should have undertaken the agreed-on competencies (click here)
Medications including adrenaline should be charted prior to commencing
There should be agreed on criteria for nurse administration of adrenaline without waiting for medical review
Hospital policies for calling for emergency back-up (resuscitation team) should be clearly understood
Prompt medical back up is essential
Prior to starting challenge the child should be well, with no intercurrent infection and asthma (if present) must be well controlled to minimise risk of challenge. If eczema and allergic rhinitis are present, they should also be well controlled to enable recognition of reaction during challenge.
Antihistamine should be avoided for 3 days prior to challenge. If on arrival a patient has taken antihistamine within the last 3 days, please discuss with consultant.
Challenge procedure
Most challenges will be standardised or modified using current ASCIA protocol (available on www.allergy.org.au )
Unusual foods or circumstances (such as multi-food allergens) may require their own protocol which should be decided on in advance.
Stopping challenge:
The challenge will stop if at any time objective symptoms of an allergic reaction occur using the PRACTALL 2012 criteria.
The purpose of challenge is to determine whether allergy is present or not, and not to establish how severe a reaction may be.
No reaction at challenge:
After consumption of their final dose the child should be observed for at least 2 hours prior to discharge.
The child and family should be advised that the food challenged can be introduced into the diet.
Advice about ongoing introduction will be given as per the ASCIA food challenge protocols.
If other food allergies are present ongoing follow up and an updated allergic reaction management plan should be arranged.
Incomplete challenges:
In certain situations, particularly in young children, it may not be feasible for the child to ingest all of the doses prescribed in the protocol.
There should be discussion with the supervising paediatrician regarding interpretation of the challenge outcome before discharging the child.
Ongoing care of children and young people with food allergy
Food allergy affects up to 10% of preschool age children and up to 5% of high school age young people. There is no treatment and the food(s) concerned must be avoided to prevent reactions. Food allergic reactions can result in anaphylaxis, which is potentially life-threatening. Ongoing care requirements need to be considered with respect to:
Follow up
School
Transition
Follow up
All children and young people with food allergy need follow up. The frequency of follow up will be determined by the age of the child or young person, their clinical history, and the food(s) involved.
Why?
The purpose of follow up includes:
To assess possibility of resolution of the food allergy
This may be determined by interval history - if there has been a recent unequivocal reaction on accidental exposure to the food then the allergy is clearly persistent
Allergy skin prick tests or serum specific IgE may also help decide the likelihood of resolution.
Referral for supervised food challenge may be appropriate if the tests or history suggest that the food allergy may have resolved.
To review risk management
Age appropriate strategies should be discussed
"5 for 5" is aimed at families with new school entrants
https://250k.org.au has resources for teens
Anxiety is a common problem for children and young people with food allergy and may need to be addressed
When?
The timing of follow up will be influenced by :
The food
Some food allergies may resolve more quickly so review every 6-12 months in early childhood may be appropriate (eg milk, egg, wheat, soy)
Resolution of allergy occurs in about 10-20% of peanut or nut allergy, and about 10% of fish or shellfish allergy. Re-evaluation every 2-3 years may be appropriate
Children avoiding nutritionally important foods (e.g. milk or wheat) in early childhood may need more frequent review including dietetic input
The child or young person’s age
Starting school is often a milestone where action plans and risk management needs to be reviewed
Similarly, teens may need review to ensure appropriate transition of responsibility
Where?
Paediatrics versus primary care
Allergy skin testing for many allergens is not routinely available in community settings around New Zealand, so care through paediatric services may be needed.
Follow up often requires access to secondary services such as dietetics and supervised food challenges.
Follow up in primary care is an option where the child or young person’s doctor is able to provide ongoing review of the possibility of resolution of the allergy, and where they can ensure appropriate review of action plan and risk management.
Follow up with Dietetic Services may be available through Primary Health Organisations or Community Services, depending on the region.
School
Early childhood services and schools are responsible for the health and safety of children and young people in their care. In order to meet their obligations they require current medical information and an ASCIA Allergy or Anaphylaxis Action Plan filled in and signed by the child’s doctor (specialist or GP) or nurse for any child identified as having food allergy.
Children with food allergy should be regularly reviewed, as some allergies resolve over time (refer ‘Food allergy follow-up practice recommendation’). Risk management strategies need to be age appropriate, with appropriate gradual transition of responsibility.
Allergy review prior to starting school
Consider paediatric review at 4 – 4 ½ years with a view to getting child ready for school
Repeat allergy testing if appropriate – is the child still allergic?
Update ASCIA action plan
Review medications (antihistamine dosage and adrenaline autoinjector) and provide prescriptions and / or ordering information
Review asthma control (if relevant)
Discuss developmental aspects with the parent (click here)
Allergy review prior to starting secondary school
Repeat allergy testing if appropriate – is the young person still allergic?
Update ASCIA action plan
Review medications (antihistamine dosage and adrenaline autoinjector) and provide prescriptions and / or ordering information
Review asthma control (if relevant)
Discuss transition or responsibility with young person and their parents
Consider whether anxiety is an issue and needs to be addressed
250k is an excellent resource specifically designed for young people with persistent food allergy
Resources for Patients, Families and Carers
Ensure that the family obtains and is instructed in the use of an autoinjector. Currently the only adrenaline autoinjector available in NZ is the EpiPen®.
See adrenaline autoinjector ordering information
Free online training on recognition and management of anaphylaxis, and how to use an EpiPen, is available on https://anaphylaxis.ascia.org.au/
A family can register their EpiPen device with EpiClub to be sent a free trainer EpiPen device plus reminders of expiry date.
Schools can also register and get a free education pack.
Advise the family in respect to ACC claims for anaphylaxis. Refer to Allergy New Zealand for more information.
Resources for schools include:
ASCIA Guidelines - Prevention of Anaphylaxis in Schools, Preschools and Childcare: 2015 update (click here).
The Ministry of Education has a ‘Guide to Allergies’: https://www.inclusive.tki.org.nz/guides/allergies-and-learning/
Various regions have different availability of education available for schools and preschools, generally through the local public health service. Check with your local PHN team if unsure.
Resources for schools including an EpiPen® training device are available through EpiClub
Allergy NZ education resources (http://www.allergy.org.nz/shop/Education+sector.html )
Transition and transfer to adult care
Adult clinical immunology and allergy services in New Zealand are based in Auckland, Wellington and Christchurch, with outreach services also in Whangarei.
Age of transition is locally determined but generally towards the end of secondary school (16 -18 Years)
Resources for transition are available at ASCIA Transitioning from Paediatric to Adult Care for Severe Allergies
Resources for young people with food allergy are available at https://250k.org.au
Ongoing care of young people with food allergy can be provided in primary care. It is suggested there should be annual review of food allergy including:
Review interval history
Have there been any allergic reactions, and if so how were they managed.
If there has been ingestion without reaction this could indicate possible improvement / resolution of the allergy
Consider whether further tests are needed
Consider whether food challenge could be considered
Referral to local / regional allergy service may be indicated
Update action plan www.allergy.org.au
Review correct use of adrenaline autoinjector
Plan follow up of food allergy on an annual basis