Health

Warning over 'dodgy' allergy tests

Child will allergy Image copyright Science Photo Library
Image caption Allergies may be being blamed for other conditions

A leading scientist warns that not all allergy tests do what they say. In this week's Scrubbing Up, Stuart Jones - principal biochemist at King George Hospital, London - calls for more regulation of the sector.

More and more consumers are being duped by diagnostic tests that are unproven, misleading and, in some cases, of no scientific basis whatsoever.

All manner of diagnostic tests can now be bought directly from online retailers or high street stores, without any input from a regulated health professional.

The consequence is that people often receive incorrect medical diagnoses and inappropriate or potentially harmful treatments that they do not need.

'Over-diagnosis'

The issue is perhaps most poignant when dealing with allergy, as the charity Sense About Science emphasise in their 'Making Sense of Allergies' guide, published last week.

In it they highlight the extent to which the misconceptions around allergies are resulting in essential information and life-saving actions being diluted in a sea of over-diagnosis.

In some cases clinicians are even seeing children with malnourishment because of unnecessary dietary restriction following an incorrect diagnosis of food allergy.

Of course the serious health threat that genuine allergy poses should not be trivialised; across Europe there were seven times as many people admitted to hospital with severe allergic reactions in 2015 than in 2005, and UK hospital admissions for anaphylaxis increased 615% between 1992 and 2012.

Allergies are now better diagnosed but there is concern that allergy has also become a catch-all diagnosis for unexplained symptoms.

A study of 969 children showed that 34% of parents were reporting food allergies in their children when in fact only 5% had an allergy.

'Meaningless' tests

Dubious 'over-the-counter' tests are a major factor contributing to this problem. Search the web for an "allergy test" and you are presented with a bewildering array of tests that are available at a click of a button, no doctor required.

You might not realise that many of those on offer, such as hair tests, 'bioenergetic' analysis and applied kinesiology, have no scientific basis and provide absolutely no information about allergy.

Others can be very misleading, such as tests for "food intolerance", which can cost upwards of £300 and measure levels of food specific IgG antibodies in the blood.

But these results are frequently high in perfectly healthy individuals, and the test is widely considered meaningless.

The National Institute for Health and Clinical Excellence (NICE) specifically lists the tests that should not be used to diagnose allergy or food related complaints. All these tests are included.

The clinically valid tests they do recommend are:

  • blood IgE testing,
  • skin-prick testing
  • challenge testing (only rarely done)

All of these need to be performed and interpreted by a qualified health professional.

What concerns many laboratory and medical specialists is the regulatory flaws that continue to expose patients to potentially harmful tests.

Image copyright Science Photo Library
Image caption Experts say allergy tests should be done by qualified clinicians

Many of the devices used to perform tests such as Bioenergetic analysis are not 'CE marked' for medical use - the legally required EU stamp of approval - yet they remain widely available.

Although, CE marking itself is no guarantee that test results will be meaningful.

Most food-specific IgG antibody tests carry a CE mark and yet results are widely considered to be of no clinical value.

This is because EU legislation does not require the test to be clinically meaningful, only for it to measure what it says it measures.

Prosecutions rare

Of course there are consumer protection laws in the UK that should in theory protect patients from misleading tests but prosecutions are almost unheard of.

Surprisingly, perhaps the most effective regulator in the UK has been the Advertising Standards Authority (ASA), which has upheld a large number of complaints against companies selling unproven tests forcing them to remove or modify misleading promotional material.

Unfortunately, this is often merely damage limitation as the tests are typically still offered but with updated advertising.

Until regulators get tough on manufacturers and retailers of dubious 'over-the-counter' tests patients will continue to be misled and harmed whilst genuine life-saving information about conditions like allergy will continue to be diluted.