Evidence-Based Versus Non Evidence-Based Allergy Tests and Treatments - Frequently Asked Questions (FAQ)

pdfASCIA PCC Evidence-Based vs Non Evidence-Based Allergy Tests-Treatments FAQ 2021141.12 KB

Q 1: What is required for an accurate diagnosis of allergies?

Allergy is a science and evidence-based medical speciality, which relies on understanding the biological mechanisms of allergic disorders, including asthma, allergic rhinitis (hay fever), food allergy, insect venom allergy, drug allergy, atopic dermatitis (eczema) and severe allergic reactions (anaphylaxis).

Accurate diagnosis of allergies requires an examination of a person’s clinical history, including symptoms that may be caused by allergies, by a qualified medical practitioner, combined with proven, evidence-based and reliable allergy testing to confirm the diagnosis. Test results alone may not always be relevant. 

When considering allergy tests and treatments, advice needs to be ‘evidence-based’. This means that there needs to be evidence that a particular test or treatment is reliable, based on studies of other patients with similar conditions.

Q 2: What are proven, evidence-based allergy tests?

Proven, evidence-based allergy tests are:

  • Skin prick tests and blood tests that measure allergen specific antibodies known as immunoglobulin E (IgE), which should always be considered alongside the clinical history.
  • Food or drug allergen challenges. being given the food or drug thought to have caused the reaction), which should always be medically supervised using published, consistent protocols, to confirm or exclude food or drug allergies.

Q 3: Why does ASCIA strongly advise against the use of online allergy testing services?

Even if proven tests and treatments are ordered online, advice should not be given without a consultation with a qualified medical practitioner, to review the condition and clinical history. This is because test results may not be relevant to the allergic condition, for example, food allergy tests are not required for hay fever.  

Q 4: What are proven, evidence-based allergy treatments?

Immunotherapy is a proven, evidence-based treatment which is close to being a cure for allergy. It has been shown in published studies to reduce the severity and frequency of symptoms in most people.

  • Allergen immunotherapy (AIT), by injections or sublingual tablets/liquids, in people with hay fever or allergic asthma with a confirmed allergy to inhaled allergens (such as pollen and dust mites).
  • Venom immunotherapy (VIT), by injections in people with severe allergic reactions to stinging insects (bees, wasps, ants).

Other proven allergy treatments include adrenaline (epinephrine) for treatment of life-threatening anaphylaxis, non-sedating antihistamines and corticosteroid nasal sprays.

Allergen minimisation can be used to reduce exposure to inhaled allergens, whilst allergen avoidance is used to manage food, insect and drug allergy.

Oral immunotherapy (OIT) for food allergy is not currently a routine treatment in Australia and New Zealand. There are ongoing clinical research trials being conducted, to ensure that it is safe and effective.  

Q 5: What are unproven, non evidence-based allergy ‘tests’ and ‘treatments’?

ASCIA strongly advises against the use of unproven, non evidence-based allergy ‘tests’ and ‘treatments’ that are provided by some unorthodox/alternative practitioners. There is currently no stringent government regulation of these methods, which include Vega (electro-diagnostic), bioresonance, cytotoxic, Bryan’s or Alcat tests, hair analysis, VoiceBio, kinesiology, allergy elimination and Immunoglobulin G (IgG) to foods.

Q 6: What adverse outcomes are due to unproven, non evidence-based allergy ‘tests’ and ‘treatments’?

Adverse outcomes due to the use of some non evidence-based allergy ‘tests’ and ‘treatments’ include:

  • Impact on employment and social functioning, due to unnecessary avoidance of ‘allergens’.
  • Impaired growth, food anxieties and malnutrition, due to unnecessary avoidance of foods.
  • Delayed access to more effective diagnostic tests and treatments for allergic disorders.
  • Lost productivity and income from inadequately controlled allergic disorders.
  • Significant costs to person without allergies who is incorrectly diagnosed as having allergies.

Q 7: What questions should you ask providers of unproven allergy tests and treatments?

In the absence of government regulation of unsubstantiated claims for unproven, non-evidence-based allergy tests or treatments, patients should ask the same questions they ask about any tests or treatments before going ahead:

  • What is the evidence it works?
  • What are the risks and benefits?
  • What might happen if I do not undertake this form of treatment?
  • How much does it cost?
  • Are there any side-effects?
  • Why doesn’t my own doctor suggest this type of treatment?
  • What are the qualifications of the practitioner recommending the treatment?
  • Why can this one test of treatment detect or treat so many different problems?
  • Is there a Medicare rebate for this test?

Q 8: Where can further information be obtained?

© ASCIA 2021

ASCIA is the peak professional body of clinical immunology/allergy specialists in Australia and New Zealand.

ASCIA resources are based on published literature and expert review, however, they are not intended to replace medical advice. The content of ASCIA resources is not influenced by any commercial organisations.

For more information go to www.allergy.org.au

To donate to immunology/allergy research go to www.allergyimmunology.org.au

Allergy Testing

pdfASCIA PCC Allergy Testing 2020144.2 KB

Avoiding or minimising allergic triggers is an important part of allergy and asthma management. Allergy testing using skin prick tests or blood tests for allergen-specific IgE helps your doctor to confirm the substances to which you are allergic, so that appropriate advice can be given.

When allergy testing is appropriate

Allergy testing is usually performed on people with suspected allergic rhinitis (hay fever), asthma or reactions to insects or foods. In people with allergic rhinitis or asthma, allergy testing usually includes house dust mite, cat and dog dander (or other animals if contact occurs), mould spores, pollen from relevant grasses, weeds or trees and in some cases, occupational allergens. Testing can also be used to confirm suspected allergies to foods, stinging insects and some medicines.

It is important to note that:

  • Allergy test results cannot be used on their own and must be considered together with your clinical history.
  • Medicare rebates are available for skin prick tests or blood tests for allergen specific IgE (formerly known as RAST) in Australia.
  • In some cases, you may be referred to a clinical immunology/allergy specialist for further detailed assessment.

Skin prick testing

Skin prick testing is the most convenient method of allergy testing. It has been shown in clinical studies to improve the diagnosis of allergy. As results are available within 20 minutes, this allows you to discuss the outcome with your doctor at the time of testing.

Tests are most commonly performed on the forearm or the back. The skin is first cleaned with alcohol and may be marked with numbers corresponding to the allergens. Using a sterile lancet, a small prick is made through a drop of allergen extract. This allows a small amount of allergen to enter the skin.

If you are allergic to the tested allergen, a small itchy lump (wheal) surrounded by a red flare will appear within 15-20 minutes.

Skin prick tests are slightly uncomfortable but are usually well tolerated, even by small children. Local itch and swelling normally subside within one to two hours. More prolonged or severe swelling may be treated with a non-sedating antihistamine, a painkiller tablet and/or a cool compress. Occasionally people will feel dizzy or light-headed and need to lie down. Severe allergic reactions from allergy testing for asthma or allergic rhinitis (hay fever), are very rare.

Skin prick testing should only be performed by a health professional who has been trained in the procedure and who knows how to select the allergens, interpret the results and manage any generalised allergic reaction that may occur. Allergic reactions to skin prick testing are rare.

Antihistamine tablets/syrups or medications with antihistamine-like actions (such as some cold remedies and antidepressants) should not be taken for three to seven days before testing as these will interfere with the results. You may also be advised to avoid creams and moisturisers on your forearms or back on the day of the test, to reduce the likelihood that allergen extracts will run into each other.

Skin prick testing has no value in the investigation of suspected reactions to aspirin, food additives, or respiratory irritants like smoke or perfumes.

Other skin testing methods

Intradermal testing (also known as scratch testing) should not be used to test for allergy to inhalants or foods. Instradermal testing was used in the past, however it is less reliable than skin prick testing, and causes much greater discomfort. Intradermal skin testing may be used to test for allergies to antibiotic drugs or stinging insect venom, when greater sensitivity is needed. 

Blood tests for allergen specific IgE

Immunoglobulin E (IgE) antibodies directed against specific allergens can be measured with a blood test. These tests are often performed when skin testing is not easily available, when there is a skin condition such as severe eczema, or when a person is taking medications (such as antihistamines), that interfere with accurate skin prick testing.

Total IgE testing

Total IgE antibodies may be raised in people with allergies, and can be measured from a blood sample.  High total IgE levels are also found in people with parasite infections, eczema and some rare medical conditions. High total IgE levels do not prove that symptoms are due to allergy, and a normal total IgE level does not exclude allergy. Therefore, measuring total IgE levels is not routinely recommended in allergy testing.

Eosinophil counts

Eosinophils are specialised white blood cells that are designed to kill worms and parasites. They can also cause tissue inflammation in allergy. High levels are sometimes seen in blood samples from people with allergic rhinitis (hay fever), asthma and eczema, as well as other less common conditions. However, a high eosinophil count does not prove that symptoms are due to allergy, and a normal eosinophil count does not exclude allergy. Therefore measuring eosinophil counts has a limited role to play in allergy testing.

Patch testing

Patch testing is useful for testing for allergic contact dermatitis, that can be triggered by metal, cosmetic preservatives or various plants. It involves applying patches with test substances in small chambers or discs to a person's back, which are secured with hypoallergenic tape. The tapes are left in place for 48 hours and kept dry for the entire time. The test site is then read at different time intervals. An eczema-like rash can indicate sensitivity to a particular allergen.

Oral allergen challenge testing

Oral allergen challenge testing may sometimes be required to confirm diagnosis when the cause of a severe allergic reaction has not been confirmed. This will normally only be performed using foods or medications under the supervision of a clinical immunology/allergy specialist with appropriate resuscitation facilities immediately available.

Unproven methods

There are several methods that claim to test for allergy and many of these are offered as online allergy tests, which ASCIA does NOT recommend. Unproven methods include cytotoxic food testing, kinesiology, Vega testing, electrodermal testing, pulse testing, reflexology and hair analysis. 

These methods have not been scientifically validated and can result in misdiagnosis and ineffective treatments, leading to unnecessary, costly and (in the case of some changes in diet), dangerous avoidance strategies. No Medicare rebate is available in Australia for these tests and the use of these methods is not recommended.

 

© ASCIA 2020

ASCIA is the peak professional body of clinical immunology/allergy specialists in Australia and New Zealand.

ASCIA resources are based on published literature and expert review, however, they are not intended to replace medical advice.

The content of ASCIA resources is not influenced by any commercial organisations.

For more information go to www.allergy.org.au

To donate to allergy and immunology research go to www.allergyimmunology.org.au/donate

Updated July 2020

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