How do I take part in the study?
You will need to be referred to us by your doctor at St Thomas’ Allergy Department or one of the Allergists from The Portland Hospital with a suspected or confirmed allergy to milk, egg, cashew or sesame.
Why does my child need a food challenge?
As you know, we regularly use allergy tests such as skin prick tests and blood tests (often called IgE or RAST testing) to guide us in diagnosing food allergies. However, there are limitations to the usefulness of these tests particularly in young children as they do not always accurately predict whether a child is truly allergic to a particular allergen. Therefore, an oral food challenge is often required to confirm whether your child is tolerant or allergic to the food tested. It is considered the ‘gold standard’ diagnostic test and is currently the most accurate and safest way for us to diagnose food allergies. In the BAT 2 Study we will be comparing the diagnostic accuracy of the new Basophil Activation Test (BAT) with that of the food challenge test, to see which is better for diagnosing food allergies to cow’s milk, egg, sesame and cashew nuts. The BAT is a blood test which requires a small sample of blood and looks at whether basophils, which are blood cells involved in allergic reactions, react to food allergens.
My child is already eating baked egg/ baked milk, so I would only like to come in for the loosely cooked egg/ fresh milk challenge, can my child still take part in the study?
In order to proceed with the loosely cooked egg or fresh milk challenges your child will need to do the baked egg/milk challenge with us first even if these foods are currently consumed. We will request that all forms of egg/ milk are avoided for 2 days before coming in for the challenge.
What happens if my child reacts to the challenge food?
Experienced allergy doctors and nurses will closely monitor your child during the food challenge. This means they will be able to identify any mild symptoms of an allergic reaction just as they are beginning. Appropriate medication will then be given to reverse the allergic reaction in the early stages. Early, mild reactions are easily treatable with an antihistamine e.g. Chlorphenamine (Piriton) or Cetirizine. In the unlikely event of a more severe allergic reaction, oxygen or adrenaline (e.g. Epipen, Jext, Emerade) will be available to treat the symptoms. We will then continue to monitor your child for at least 2 hours after the reaction and until their symptoms have completely resolved. If your child has an allergic reaction during their food challenge, you will be given detailed advice on how to manage their allergy before you go home.
Should I give my child breakfast on the day of the challenge?
Yes, please give your child breakfast as normal on the day of the challenge. The food challenge part of your visit will usually start about 2 hours after you arrive. The first few doses are very small and will not fill them up. The larger doses will start to be given about 2½ hours after you arrive for your visit. So, a good breakfast should help prevent your child becoming overly hungry in the early stages of the challenge.
Can I give my child any other food during the challenge?
Occasionally, we may ask you to bring with you some of the foods your child likes and already tolerates (e.g. their usual milk/infant formula, yogurt, or milk/dairy free substitutes) to mix with the challenge food to help them eat it. . It is important that your child manages to eat all of the challenge food for us to be sure that they will be able to safely tolerate a typical age-appropriate portion of the food in ‘real life’. The first few doses in the double blind challenge are very small but your child will probably struggle to eat the larger later doses if they have eaten extra snacks during the challenge.
Therefore, please avoid giving your child any other food or drink (except water or fruit juice or squash) during the food challenge unless this has been agreed with the nurse or doctor in charge.
If your child eats other food or drink during the challenge and develops any allergic symptoms, it will make it more difficult for us to be sure which food is the cause of their symptoms.
What happens if my child is hungry during the challenge?
We will try to use games or other distractions to help your child to wait until it is time for their next dose of food. If your child is unable to wait for the next food challenge dose, they may be allowed to eat a light snack (e.g. fresh fruit, fruit purees, fruit jelly, rice cakes, plain crackers or plain biscuits). Please make sure that any snacks you bring for your child are foods they have previously eaten on a regular basis. However, we would prefer that you only use these snacks as a last resort and always ask the nurse or doctor in charge before giving your child anything to eat or drink other than the challenge foods, water or juice.
Will any other food and drink be provided on the day?
We can provide water and fruit squash but are unable to provide anything else other than the food and drinks given during the food challenge. Therefore, we recommend that you bring along some food and drink for your child to have once the challenge is completed. It is also advisable to bring something for yourself too. However, if you do not wish to bring your own food, hot and cold food is available to buy from the hospital canteen, cafes and shops.
How can I be sure the challenge foods do not contain any foods my child is known to be allergic to?
We will contact you by phone to review your child’s food allergy history before you come for the challenge. We will also ask you to confirm whether your child has an allergy or intolerance to any of the ingredients and whether they have any particular feeding issues, food aversions or special dietary requirements. This will give us plenty of advanced warning if we need to arrange for alternative challenge foods to be available on the day.
Is there anything else I need to bring on the day?
Your visit will be between 4- 7 hours, depending on which type of food challenge your child has and whether or not your child has a reaction. We will have some toys and DVDs to keep your child occupied. However, you may like to bring some of your child’s own favourite toys, DVDs, story books or a comforter and also something to occupy yourself such as a tablet, book or magazine.
