Why Both Misdiagnosis or Inappropriate Allergy and Intolerance Tests Can Harm Children

I have been writing a lot about allergy and intolerance tests recently; a number of factors have contributed to this. The House of Lords is currently scrutinising allergy and intolerance in the UK. When I look through the medical histories of the children with whom I work, in 60-80% of them, the parents have usually indicated that there are several allergies and intolerances. I would estimate that there is clinical confirmation of these allergies etc. in fewer than 2% of the children.

It is breathtakingly difficult to obtain a referral to a clinical allergist in the UK. In the whole of the UK, we have the equivalent of 26.5 consultant posts: approximately 5 of those are specialists in paediatric allergy. It is frequently argued that the lack of NHS allergy diagnosis and management pushes people who suspect that they have allergies towards the more dubious fringes of CAM or to testing laboratories that claim clinical validation and "sound science" for their product range of tests.

Both allergies and intolerances can have a dramatic and deletrious impact on quality of life. Allergy can kill. It is difficult to write about less severe forms of allergy because it is not practical to predict whether or not a mild allergy might suddenly become a life-threatening allergy.

A number of children 'grow out of' allergies. Some children have allergies that are multi-systemic and this puts them at particular risk. Allergies are typically managed, not cured. An exception to this is the laborious process of immunotherapy for some allergens which is rarely available on the NHS in the UK and is reserved for those people for whom medical management has failed.

Dr. Glenis Scadding is a consultant allergist with an fine reputation. She has clearly and elegantly stated that IgG tests for the diagnosis of food intolerance are "a waste of money". She has criticised the availability of direct-to-consumer IgE tests because they lead to "mis-diagnosis and mis-allergen avoidance". When she gave testimony to a recent House of Lords SubCommittee meeting she gave an excellent example.

(This recording of the SubCommittee meeting on 15 March 2007 is available from the archive for 28 days: thereafter, an authorised transcript will be available. I have used CM to indicate that the speaker is a member of the House of Lords' SubCommittee. Any punctuation, emphases or mistakes in the transcript are mine.)

Start transcript.

CM: Tell us what you think about self-testing kits and whether they should be-are they sufficiently-regulated?

Dr. Scadding: They should be banned.

[Laughter.]

Dr. Scadding: I'm very sorry...But...For example, I saw a child this morning before coming here and she had...We did skin tests that are well recognised and she had skin tests to house dust mite and also to tree pollens. Two kinds of tree pollen. She has absolutely no symptoms referable to the tree pollen whatsoever. She does not have Spring Hayfever. She has good symptoms related to the house dust mite, so I treated her with house dust mite avoidance and anti-allergy therapy.

If she had got a kit, then she would have felt that she was tree pollen allergic as
well and something had to happen about that. She has sensitisation but not clinical disease. And if you do a test, only about half the people with that positive test will have clinical disease.

So, you can not have self-testing kits: they're going to lead to mis-diagnosis, mis-allergen avoidance. You need both the test and a detailed history taken by somebody who has some experience of allergy history taking and interpretation of tests.

End transcript.

Dr. Scadding regularly sees children who have suffered clinical harm, e.g., unnecessary surgical procedures such as tonsillectomy, adenoid removal, the placement of grommets etc. when the real problem has been undiagnosed, and therefore untreated, allergy. Later in the meeting, Dr. Scadding answers a question about inappropriate treatment.

Transcript starts.

CM: Dr. Scadding, how often do you see patients whose treatment has been inappropriate? I'm not talking about the ones where the allergic allergen has been missed but where they've actually been treated inappropriately for their allergy and have therefore come to clinical harm before they're referred?

Dr. Scadding: At least once a week-and often more than that.

CM: And what are the main causes?

Dr. Scadding: The main causes are that they have been unrecognised or under-treated or treated for something other than allergy.

End transcript.

In addition to clinical harm, children who are mis-diagnosed with allergies or intolerances may follow a very restricted diet that might not provide all of the nutrients that they need and may lead to malnutrition. So, I apologise in advance, but I shall be covering the topic of allergy and allergic diseases in children for some time to come.