Egg allergy is common, affecting 2-3% of UK children and can cause severe allergic reactions and accidental exposures are common. Egg allergy is often outgrown during early childhood, but in some children can persist in later teenage years or even early adulthood. Until recently, the standard treatment has been careful avoidance. This is starting to change and there has now been a 15-year history of medical research into desensitisation to egg.
What is Oral Desensitisation?
Oral Desensitisation (OD), also known as Oral Tolerance Induction (OTI or OIT) or food desensitisation, is a treatment that involves giving very small, but gradually increasing amount of the food that the child is allergic to. The intention of OIT is to increase the tolerance to egg so that larger amounts of egg can be taken without causing any symptoms and as a result, egg containing foods can be eaten safely or at very least, accidental exposures to small amounts of egg will not cause reactions. This treatment has been most studied for milk and egg and is also the subject of intensive research for peanut allergy.
It is important to recognise that this treatment leads to a state of desensitisation (a temporary state, where greater amounts of egg can be tolerated without symptoms) and not necessarily true ‘tolerance’ (a permanent state where any amount of egg can be consumed without any risk of reaction). In practice, this means that the regular doses of egg must be continued consistently in the long term for the treatment effect to remain. If it isn’t, the risk of reaction returns, although over time, development of genuine tolerance (outgrowing of the allergy) is still likely.
How effective is oral desensitisation?
There are numerous studies from around the world as well as systematic reviews (where the results of lots of studies are combined) that demonstrate that OIT works well for milk and egg. Different studies use different approaches, in different children but in the 2 of the best conducted studies, 75-91% of children were able to consume large quantities of egg.
Children tend to have 3 possible responses to treatment:
1) they achieve a full, high dose that they can tolerate without any problem
2) They can’t reach the full dose without persistent side effects but can still tolerate a useful amount of egg without reactions
3) they are unable to progress at all due to side effects.
The protocol we use is based on one developed by a Paediatric Allergy team in New York at Mount Sinai Hospital. Studies are starting to show that children with very high skin prick or blood allergy tests to egg are less likely to find the treatment to be effective, or will be more likely to have side effects, and this will be considered at any assessment. Multiple studies have also shown a clear improvement in quality of life for both children and parents, where OIT has been performed.
As part of any assessment process, we will discuss where OIT may be more appropriate to be performed be. For lower risk patients, this can be done in our clinic facilities but for those where the risk is higher, due to a history of severe reactions or sensitivity to very small amounts of egg, our day-case facility at Great Ormond Street Hospital, through our sister practice, The Food Allergy Immunotherapy Centre, may be more appropriate. If this is required, it will have a cost implication.
How safe is oral desensitisation?
There has been a lot of concern around safety of this treatment, because of the known risk of severe allergic reactions that could happen to foods. Most, if not all children, will have some allergic reactions during the treatment but these are virtually all mild. Typical reactions are rashes, lip/face swelling and abdominal discomfort and less commonly, wheeze. Severe reactions, requiring adrenaline are reported in a small number of patients in the published studies but with this treatment now widespread in Europe and the US, it is very reassuring that there have been no reported fatal or near fatal reactions reported to baked egg OIT. However, there are several clear ways that the risk of severe reactions can be reduced, and many lessons have been learned for the severe reactions that have occurred. The most important influence on safety is the actual desensitisation protocol. Some studies are focussed on a rapid dose increase, with multiple hospital visits. This can mean the treatment works much more quickly but carries a greater risk of reactions. The protocol we use is much slower and, therefore, reactions are less likely, but has the disadvantage of being slower, taking 4-6 months, although the time between doses can be varied from a minimum of 2 weeks to much longer.
Our approach is to prioritise safety over speed. It is impossible to desensitise without any risk of allergic reaction, which means that for some families, this will not be the right approach. However, ensuring parents are fully trained to manage severe allergic reactions in the unlikely event that they happen (patient will be prescribed and trained to use an adrenaline auto-injector (eg Epipen) where appropriate), and observing some simple rules around dosing, will reduce the risks of the treatment significantly. The risk of reacting must also be considered in the context of the risk of severe reactions that may happen if the child were not desensitised and had an accidental exposure.
There is also a concern that OIT can result in the development of eosinophilic oesophagitis (EoE – an inflammatory condition of the oesophagus) and other food-induced gut related problems. A systematic review reported EoE in up to 2.7% of patients undergoing OIT for IgE mediated food allergy (although the review is based on incomplete datasets, because most trials of OIT have not reported the presence or absence of EoE as a longer-term adverse event) although as EoE is known to disproportionately affect children with allergies anyway, there is no evidence yet of a causative link.
Currently, international guidelines on the management of food allergy state that OIT to milk, egg and peanut can be offered by allergy specialists, reflecting our improved understanding and the experience of the many doctors. Many allergy specialists in Europe and US are now offering this treatment.
What does oral desensitisation treatment involve?
The process can be broken down into a series of parts:
- Assessment – following a confirmed diagnosis, an assessment is required to introduce the concept of desensitisation, consider if it is suitable for your child and whether it is something you would like to consider. This is a process of shared decision making, that includes provision of information such as this document as well as a conversation about risks, benefits, and alternative options. This may happen as part of a routine appointment or sometimes a separate, more focussed appointment is arranged. The assessment will involve a detailed history and examination focussing on the egg allergy and may require skin prick or blood tests for egg allergy if these have not been done for more than 6-12 months. It will also require a detailed asthma assessment and where appropriate, lung function testing as any child whose asthma is not extremely well controlled, would not be suitable for treatment. If your child is over 14 months and has never been exposed to baked egg, it may be necessary to clarify if your child is able to tolerate this, by consuming an egg containing fairy cake under supervision. If they can, this suggests a different, easier strategy for desensitisation may be used (regular consumption of baked egg). If your child cannot tolerate egg in the baked form, and is otherwise suitable, then the treatment can be considered.
- Initial introductory session – this is the start of the process and involves a detailed discussion with our specialist dietician and will cover areas such as how to make and correctly measure the doses needed, how to manage reactions and all the other logistical aspects of the treatment. This session may take place in person or virtually. You will be provided with written information to support what you learn. There is also an option to do this in 2 parts, to ensure you know as much about the treatment as you wish too, before committing. This means that you would pay for an initial session with he dietician but if you progress with the treatment, the cost of the session will deducted for the overall cost.
- Consent – if it is felt your child is suitable for the treatment, you will be asked to sign a consent form to indicate that you have fully understood the risks involved. Treatment cannot start without this, but you have no obligation to continue the treatment and can stop at any time. A copy of the consent can be found at the end of this document.
- Treatment Initiation – This would start with an initial visit where the first, small amount of baked egg is given under medical supervision by one of our specialist nurses or doctors, with Prof Fox also present. You will also be prescribed an adrenaline auto-injector (eg Epipen) and trained how to use it (if you don’t already have one), in case of a more severe reaction. If this first dose is tolerated, you will be asked to give the same amount of baked egg every day at home for around a month. You will be given details of exactly when and how to do this and what to do if there is any reaction. You will have contact details with an assured 1-day response time, for queries where an answer is required before the next day’s dose as well as a regular check in call.
- Updosing – If home dosing goes well, then you will come back to clinic, under the supervision of our team, to try a bigger dose. If this is well tolerated, you will then give the same dose daily (or at least 5-6 times per week) at home for a further month before returning. The schedule usually includes 5 supervised dose increases. After successful increases, your child should be able to tolerate the equivalent of one third of an egg in baked form, and after a period of 3 to 6 months at this level, a boiled or well-cooked scrambled egg can be trialled as an in-clinic food challenge.
- Maintenance – If the treatment has been successful, a further appointment with our specialist dietician is scheduled to discuss integrating baked or plain egg into the regular diet. Regular exposure is required to maintain the effect of the desensitisation. This means your child will need to include baked egg in their diet daily.
- Follow up – an annual follow up is recommended to monitor progress, specifically for signs of improved tolerance to egg that would allow for further relaxing of the diet.
What if it doesn’t work?
This treatment does not work for everybody, but if the dose cannot be increased above a certain point because of recurrent side effects, then this dose can be continued for 3 months and then increasing the dose can be attempted again. This can often be successful. Even if only limited desensitisation is achieved, this can still protect from reactions due to accidental exposures. It is also possible for smaller doses, if required daily for a long period, to be changed to an easier alternative or to provide another option to prevent taste fatigue eg baked egg pancake.
Is egg oral desensitsation treatment the right thing for my child?
OIT is not right for everyone. If your child has suffered severe reactions, especially to very small exposures to egg or has poorly controlled asthma or other illnesses, then this treatment is not suitable. If your child’s allergy tests are very high (eg skin test >9mm or IgE >50) then this increases the change of problematic side effects and reduces the chance that the treatment will be successful. If you are unable to commit to very reliable daily dosing, then this would not be suitable. Your child also needs to accept the regular intake of the baked egg containing food. If your absolute priority in managing your child’s egg allergy is avoiding any reactions, then a policy of strict avoidance is probably best. If you are prepared to accept a regular daily treatment, with occasional mild allergic reactions then OIT is worth considering.
What is the cost of egg oral desensitisation?
As a treatment for allergy, it is unlikely this will be covered by your insurance, which normally only covers diagnosis of allergy although there are exceptions. We are hoping that this will also improve over time. There is a separate document which outlines the cost.
Any initial assessment for suitability for desensitisation will be charged as a regular consultation, with any tests such as skin prick testing, lung function or challenge testing charged at the usual practice rates (available on our website).
If you are unsure if you wish to progress with a desensitisation process, an initial detailed consultation with our specialist dietician is recommended and the cost of this will be deducted from the price of the treatment if you decide to go ahead.
Once you decide to progress, there is a package cost, which includes the introductory session, treatment initiation, all up-dosing visits, ongoing support and any additional visits required (for example if there is a reaction to the initial dose and a lower starting dose is needed) as well as a final session with the dietician. The package does not include annual follow up after conclusion of the treatment. The price may be more if additional visits are required due to your child being very sensitive to egg. Refunds are available if less visits than expected are required.
In some cases, for example, where there is a history of anaphylaxis or other risk factors, there may only be the option to perform the treatment at our Great Ormond St Hospital Day Case facility. This will have a cost implication of and will be discussed beforehand, on an individual basis.
If you have any specific questions, including queries about the cost, please email us on firstname.lastname@example.org or if you would like to book an assessment visit, or a session with the specialist dietician, please contact us on 020 3758 9160 or by email.
The most useful scientific articles to read would be these:
Burks AW et al. Oral immunotherapy for treatment of egg allergy in children. New England Journal of Medicine 2012; 367:233-243
Vasquez-Ortiz M et al. Improving the safety of oral immunotherapy for food allergy. Paediatric Allergy & Immunology 2016 Mar;27(2):117-25.
Professor Adam Fox
Adam Fox is a Professor of Paediatric Allergy with over 20 years experience in both the NHS and private sector. Professor Fox is Commercial Medical Director at Guy’s & St Thomas’ Hospitals NHS Foundation Trust and Professor of Paediatric Allergy at King’s College London and the founding Director of the KCL Allergy Academy, a postgraduate educational programme, which was a finalist at the BMJ Awards in 2018.
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