I came across a very interesting and powerful editorial that summarized many issues dealing with the worldwide problem of allergy.

Allergy is a major health problem-clearly not in everyone and not in the majority of the population. Worldwide allergy affects 10-30% of people. As far as a single chronic clinical condition, that is a significant number. Also, the prevalence has increased.

The impact of an allergy can be life-threatening (acute severe episodes) or chronic (daily symptoms). The allergic condition does have a major socioeconomic burden and allergy also has the obvious effect on a patient or a family’s quality of life.

Despite advances in research on causes, associations, risk factors, and treatment of allergy there are many inadequacies and unanswered questions. This editorial shares those concerns.

This is a consensus statement from a group of 40 noted researchers and clinicians from four continents who met in Switzerland last year. The banner for the meeting was simply ‘Allergy and Allergic Diseases: Barriers to Cure’.

Allergic conditions deal with many broad areas of medicine. Allergy affects a wide range of organ systems; eyes, respiratory tract, gastrointestinal tract, and skin. The conditions vary in severity and their course.

Listed are the concerns and needs (these come from the experts and are my summations of their summation);

• The cause(s) for the increase in allergy prevalence is unknown. Environmental considerations    include; air quality, diet, climate, UV radiation, direct skin contact, and psycho-social interactions.
• A specific environment may protect or put someone at risk if they have the genetic predisposition towards allergy.
• Interactions between bacteria, pollutants, and the immune system are marginally understood.
• There is inadequate understanding of those natural mechanisms that lead to acute vs. chronic suffering with allergy or resolution of allergy.
• There needs to be a better classification system for severity/types of allergy.
• New therapies need to work on the pathways that lead to an allergic response.
• Better translational research is needed (taking what is learned in the laboratory to the bedside).
• Better tools are needed to analyze the information or data regarding allergy.
• There needs to be a plan for prevention of allergy.
• We need better tools for diagnosis and prediction of a response to treatment.

The article also noted the gap between what we know about allergy and the application of that knowledge to those who struggle with allergy.

• There is a shortage of well-trained allergists in most countries
• Education and training efforts regarding allergy need to start with the medical students, especially for a condition that affects so many people
• Awareness campaigns are needed for targeted groups such as nurses and school teachers
• There needs to be close cooperation with patient organizations
• Decision makers for developing and approving health policies and administration must be made more aware of the issues and problems of allergic diseases

Reviewer’s note-

It scary what we do not know and it is even scarier that we are not doing much about a few things when we can.

Allergy is a public health problem.

The editorial challenges us to make a change.

This year Dr. Vitalpur and I will be offering clinical teaching about the immune system and allergy in particular to first year medical students.

I have always wondered why allergy is not a required resident rotation – a requirement by the governing board of residencies. The condition affects so many children and is thought to affect so many more. I can easily see the impact of having at least a few weeks of exposure to the specialty in our allergy clinic.

We are most happy to speak at support groups or schools and we have done that many times. I am concerned that we are not asked more frequently to go out in the community.

We get involved with patient organizations and are willing to be involved with more.

It is unfortunate that we are not asked about policy or design. More often we have a reactive role in this regard.

The challenge is before us.

FEL (2-2-2012)

Practical guide to skin prick tests in allergy to aeroallergens

I was alerted to this article by my partner Dr. Vitalpur. It comes from Allergy (European Journal of Allergy and Clinical Immunology) 2011 . The purpose of the article was to provide ‘pocket guidelines’ from a consensus report regarding the use of allergy skin prick tests for inhalant or aeroallergens.

The skin prick test (SPT) is a widely used, major diagnostic tool used for the diagnosis of allergy. The introduction of the article points out the many complexities in performing SPTs and recommends that they should be performed only by trained health professionals.

As for the methods used to create the guide; it was a combined effort from the Global Allergy and Asthma European Network (GA²LEN) and the Allergic Rhinitis and its Impact on Asthma (ARIA) task force. Once the document was created, it was reviewed by the membership of the networks. The authors point out that this is not an evidence-based guideline. It should be looked at as ‘…clear-cut answers to frequently asked questions by practitioners and patients.’ The evidence-based aspect follows the guide-in future reports.

The article is broken down into a series of 21 specific questions:

1. What are the indications for skin tests in clinical practice?
2. Which skin tests are recommended?
3. What role do intradermal tests play?
4. What is the recommended skin prick test technique?
5. Which treatments suppress skin tests?
6. Which diseases affect skin tests?
7. Which allergen extracts to choose?
8. Which allergen extracts should be tested?
9. What area of the body should be chosen and what is the ideal distance between tests?
10. Which negative and positive controls are recommended?
11. Which results are regarded as positive?
12. How do skin tests compare with serum-specific IgE?
13. How to interpret skin test results?
14. Which skin tests are recommended in adolescents and adults?
15. Which skin tests are recommended in the elderly?
16. Which skin tests are recommended in young children?
17. What is the role of skin tests in primary care?
18. How can skin tests be used in developing countries?
19. Are skin tests needed in allergen immunotherapy follow-up?
20. Can skin tests be used in research?
21. What are the future needs?

Each question has a short, concise answer. These are common concerns and questions. I would like to point out a few of them for this review. The link will direct the reader to questions not covered here.

1. What are the indications for skin tests in clinical practice?

Asthma and allergic rhinitis are the indications for aeroallergen testing. The SPTs can be used from infancy to old age. The repeating of SPTs is done to detect new sensitizations in children and when changes in symptoms have occurred. 

2.Which skin tests are recommended?

Prick skin tests have a high degree of correlation with symptoms. There is high specificity (a negative test when you do not have the disease) and sensitivity (when the test is positive when you have the condition) with the skin pricks used for inhalant allergy.

 Table 1 Performance of skin prick tests

1. Use standardized extracts when available (We have grass, house dust mites, and cat as standardized extracts.)
2. Include a positive and a negative control solution (histamine is the positive control)
3. Perform tests on normal skin (not on skin affected by severe eczema or urticaria)
4. Evaluate the patient for dermatographism (Means skin writing- pressure to the skin will cause a hive, this is a common reason for someone to allergic to everything including the negative control.)
5. Determine and record medications taken by the patient and the time of the last dose
6. Record the reactions after 15 minutes
7. Measure the longest wheal diameter

Skin prick testing may cause systemic reactions

The common errors in skin testing are listed in table 2

• Tests are placed too close together and overlapping reactions cannot be separated visually.
• Induction of bleeding, leading possibly to false-positive results.
• Insufficient penetration of the skin by the puncture instrument, leading to false-negative results. This occurs more with plastic devices.
• Spreading allergen solutions during the test or when the solution is wiped away.

 3. What role do intradermal tests play?

Intradermal skin tests (when a needle is used to inject the extract- almost like a TB test) are not useful for allergy diagnosis with inhalant allergens. The clinical value is unknown in patients who only have positive intradermal tests. They are less safe to perform. There are practices where this is the only type of test done or they are performed when the SPTs are negative. We use this type of test ONLY in the ‘Bee Clinic’- the protocol for pursuing stinging insect allergy utilizes the intradermal test.

4. Which treatments suppress skin tests?

Drugs can suppress skin tests.

 Antihistamines- have a significant impact on skin test results. They should be avoided for 7 days

Imipramine- anti-depressants, sometimes used for bed wetting- can affect skin test results for 21 days

Steroid ointments and creams- minimal if any effect on skin testing

UltraViolet light – used to treat skin condition, can effect skin test results for up to 4 weeks

Table 3 Inhibitory effect of various treatments on skin prick tests show other agents that may impact skin test results.

5. Which diseases affect skin tests?

Patients with widespread eczema or hives cannot be tested in areas of affected skin. Neurological disorders and infectious diseases (e.g. leprosy) can lead to false-negative results.

6. Which allergen extracts to choose?

The quality of the allergen extract is of key importance as variations in the quality and/or potency of commercially available extracts exists, in particular for animal mites, animal dander, and molds, but even pollens. Use standardized extracts if available.  

7. Which allergen extracts should be tested?

This varies per region. This answer was relevant to Europe. I comment on this at the end of the review.

 8. What area of the body should be chosen and what is the ideal distance between tests?

Usually, the skin tests are performed on the forearms depending on the age of the patient. The distance between tests should be 2 cm. We have used the child’s back for testing. There is a larger surface area to work with. If needed, more items could be evaluated using the larger space. It is also an area which would not be frequently treated with a topical steroid.

 9. Which results are regarded as positive?

The wheal and erythema have been used to assess the positivity of the skin test. However, only the wheal is needed. The largest size of the wheal is considered to be sufficient. Wheal diameters equal to or larger than 3 mm are considered positive in SPTs.  

Redness alone is not a significant response. There needs to be a wheal (swollen area) of proper size to be called significant. In our clinic, the physician who ordered the test reads them and decides on the significance. All too often, slight red marks are interpreted as positives.

 10. How do skin tests compare with serum-specific IgE?

Serum-specific IgE, SPTs and allergen challenge do not have the same biological and clinical relevance and are not interchangeable. Low levels of serum-specific IgE are less often associated with symptoms than higher levels, but they do not exclude allergic symptoms particularly in very young children.

Note- the paper did not use the term RAST. The proper term is serum-specific IgE- that blood test for allergy. I thought that the answer to this question was not as complete as it should have been.

 11. Are skin tests needed in allergen immunotherapy follow-up?

Skin test reactivity decreases with allergen-specific immunotherapy to inhalant allergens, but skin tests cannot be used to assess the efficacy of immunotherapy in practice. Moreover, skin tests cannot be used to decide the cessation of immunotherapy.

Reviewer’s Comments-From the original 21 questions, I chose 11 that tend to be more frequently brought up in our practice. Many of the questions that I omitted dealt with issues unique to Europe or to the adult population.

In a nutshell the skin prick tests for aeroallergens (inhalant allergens) are:

• Indicated for respiratory tract symptoms
• Can be done in very young children
• Should be done with the proper extracts and application technique
• Can be done if a few medications are out of the child’s system
• There may be a problem finding clear skin to do them on a child who has eczema or hives
• May be done on the arms,
• Are considered positive if the wheal (swollen area) is of proper size (redness alone does not qualify)
• Should not be used to monitor an allergy shot program.

This was a very neat, concise, and well done synopsis of how things are done in Europe. An additional tidbit was the answer to the question- Which allergens should be tested? The quick answer is that it depends on the allergen exposure for the area and that a common, standardized battery of tests should be recommended for Europe. The list was short;

• Pollens- Birch, Cypress, Grass (one species or a mix), Mugwort, Olive (or Ash), Parietaria, Plane, and Ragweed
• Mites- two species
• Animals- Cat and Dog
• Mold- Alternaria and Cladosporium (Aspergillus extract is not available in all countries).
• Insects- Cockroach

That panel for respiratory tract allergens would contain only 15 aeroallergens plus the two controls- 17 skin tests done to assess allergen sensitization.

A reference was also made to the National Health and Nutrition Examination Survey (NHANES) performed in the United States (2005) – 10 allergens were used.

FEL

11-30-2011

When I was at Henry Ford Hospital, Dennis Ownby, MD analyzed the house dust material that was used in the immunotherapy program. Of note is that there was more cat allergen in the house dust mix than what was available in the cat preparation that was available at the time. This house dust extract came from homes. I learned that dust is a mixture of many things.

During my fellowship we went on a field trip across the state of North Carolina to Greer labs. The house dust used for allergen diagnostics and for treatment sets came from collections from a large number of homes. The house dust extract had cat, dog, house dust mite fecal material, roach, other insects, food, mold, and IgA from human spittle.

The June issue of the journal Pediatrics had a quip from the editor emeritus, Jerold F. Lucey, MD regarding the ‘Dirt on Dust’. Dust is a big deal in allergy so this interested me. The note starts with the statement that simple house dust may not be as simple as all that. His source was a text box by Andrew Grant which was part of a more elaborate article by Michael Tennesen in the May 2010 issue of Discover magazine.

Mr. Grant reports that we are responsible for our own house dust. A scientific analysis of house dust reveals that it contains fibers from clothing, crumbs from food, and human dander. Hopefully, so far this is not too disgusting.

House dust has the remnants of other living creatures- plants, bacteria, mold, fungi, decaying insect carcasses, and fecal droppings from house dust mite (yes that is poop!). Had enough? It gets worse.

Our open windows and our shoes bring in the chemical villains. A study by the US Geological Survey from January, 2010 reported on numerous harmful chemicals discovered in house dust. Included in the samples were polycyclic aromatic hydrocarbons. This is used to coat parking lots. DDT, a pesticide banned 40 years ago was detected in house dust samples. Reference was made to another study in which arsenic and lead contaminated soil was found in house dust samples. The lesson here is that we track it in to our home on our shoes.

Clearly, dust is not so simple. It is a hodgepodge of items- biological and chemical. Some can elicit an allergic response; some can cause illness in other ways.

This has caused me to wonder about dust. My wonderment has lead to a few questions;

• If the house dust has all this stuff from our shoes, I wonder what is lurking on the mat at the front door?
• Are there enough food particles in house dust to trigger an allergic reaction in someone sensitive to food?
• What is the composite listing of what is in house dust? Endotoxins would be on that list.
• What is the seasonal variation in house dust composition?
• How do various methods of cleaning change what is in house dust? Now that we have been scared, what can we do about it?
• Are certain types of homes more conducive to certain dust components.

Good studies and information always beget more questions. I am now removing my workday shoes prior to walking into my home!

Fred Leickly