Directions For Use

Directions for Use: ST-Family (also branded as AllerTest™) Multiple Skin Test Applicators and Multiple Well Test Trays

Introduction

Allergies affect approximately 1 in 5 Americans, making allergies one of the most common health problems. Allergies result in more than 17 million physician visits, 30,000 emergency visits, and hundreds of deaths annually. Increasing global temperatures are predicted to increase pollen and related airborne allergens in the coming years and therefore, the number of allergy sufferers. Allergies increase a person’s risk of other diseases, including asthma.

Allergies

An allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid. Allergy is one of four forms of hypersensitivity and is formally called type I (or immediate) hypersensitivity. Allergic reactions are distinctive because of excessive activation of certain white blood cells called mast cells and basophils that produce a type of antibody called Immunoglobulin E (IgE). This reaction results in an inflammatory response, which can range from uncomfortable to dangerous.

Prevalence

There is credible scientific evidence indicating a higher incidence of allergy occurring today than ever before. A recent report showed 54 percent of people between five and fifty-nine years of age had a positive test for at least one or more common allergens. Due to only 10 common allergens tested in this study, the reported percentage is likely to be an underestimation of the actual prevalence of allergic sensitization in the US population. This represents 139 million Americans who have the potential to suffer from allergies. Further, figures from the National Center for Health Statistics, in their most recent report, indicate that the number of asthma cases in the United States jumped 74 percent from 1980 to 1996. Moreover, it is known that an allergic reaction can be caused by the cumulative effect of several allergens being present concurrently, neither of which on its own would cause an allergic reaction.

Impact

The annual cost of allergies is said to be nearly incalculable, given the number of doctors’ visits, pharmaceutical prescriptions, lost work, and the intangible agonies that each allergy sufferer endures. In some patients, the degree of allergic reaction has caused significant lifestyle changes or even overwhelming restrictions in activity.

Testing

Skin tests have evolved as reliable, cost-effective techniques for the identification of Immunoglobulin E (IgE) mediated diseases. The technique, originally involving the placement of an allergen on abraded skin began in 1867, has now progressed to the utilization of technology to administer a known amount of allergen via percutaneous (on the skin) scratch. This allows the clinician to confirm clinical sensitivity to a range of allergens, such as pollens, weeds, grasses, trees, animal dander, molds, and many foods.

Quality & Reliability

Although generally age, sex, and race are independent, certain age (children younger than 2 years and adults older than 65 years) and racial (African American children) factors may affect interpretation. Positive (histamine) and negative (saline or 50% glycerinated–saline) should be performed at the same time as allergen tests to establish a baseline for measuring reactions.

The Patient’s Medications

A complete medical history should be collected, especially the patient’s current intake of medications. Several classes of drugs can interfere or distort the outcome of an allergy test because of their antihistamine effect. Antihistamines type drugs vary considerably in their ability to suppress a patient’s test response; therefore, the use of first- and second-generation antihistamines should be discontinued 3 to 10 days before skin tests with notable exceptions, such as cetirizine, hydroxyzine, clemastine, loratadine, and cyproheptadine. The tricyclic antidepressant doxepin may also suppress the wheal-and-flare response for as long as 6 days. Histamine2 antagonists may cause mild suppression, and their use should be discontinued at least 24 hours before testing. Oral prostaglandin D2 inhibitors (e.g., indomethacin) given several hours before testing may cause a slight increase in the patient’s response to the allergen. Skin tests should be avoided in sites where corticosteroids have been applied, or application ceased for 2 to 3 weeks before testing. See the table below for the summary of recommended intervals between the administration of the drug and testing.

Recommended Intervals Between Drug Administration & Testing:

• First-generation antihistamines: 3 days

• Second-generation antihistamines: 7-10 days

• Cyproheptadine: 14 days

• Ketotifen: 60 days

• Astemizole: 7-10 days

• Neuroleptics: 7-10 days

• Anti-psychotic drugs (tricyclic antidepressants): 3 days

Testing Site

The preferred test site is the upper back, although the volar surface of the forearms can also be used. Skin tests should not be performed in skin sites with active dermatitis or severe dermatographism. If they are performed in the presence of mild dermatographism, the results should be interpreted with caution.

Safety

The Patient

Adverse events occurring post percutaneous tests are rare but can occur. Large local reactions, both immediate and late, may cause discomfort, and occasionally, mild, non-progressive systemic reactions may be associated with the latter. To reduce the likelihood of adverse reactions during skin testing, several precautions should be taken. Pre-screening with a detailed medical history should be performed that investigates recent use of medications (see above), history of allergic reactions, history of skin disorders/complaints, and tolerance to certain foods/drugs.

The Clinician

It is imperative the clinician comply with OSHA’s Blood Born Pathogen standard: OSHA Bloodborne Pathogens Standard.

Indication for Use

The skin test applicator is used for conventional administration (percutaneous application of allergenic extracts directly onto the surface of the skin) of diagnostic allergen extracts for performing allergy skin tests on the typical sites (the back and the volar surfaces of the forearms) for hypersensitivity reactions in individuals suspected of having allergies. The test tray is intended to hold allergenic extracts in a convenient arrangement for storage and use by the clinician.

Contraindications

If the following conditions are present, the test should not be performed:

• Anaphylactic reaction (constitutional) after the previous skin test with the same allergen

• Acute fever

• Systemic disease with acute manifestation or decompensation

• Abnormal skin condition in the area to be tested (such as eczema, condition after sunbathing)

• Children younger than 3 years

• Pregnancy

Application of Test

The following directions apply to the use of the skin test applicator and multiple-well test tray (referred to as either ST-9® or AllerTest™). These products are identical in function and intended use, regardless of the brand name.

To achieve the most accurate results, it is recommended that the following techniques be developed and performed. This will ensure sufficient contact with the skin and the device is achieved, allowing the test heads of the applicator to deliver the allergenic extracts to the reactive epidermis layer of the skin. The Skin Test Applicator is designed to perform percutaneous skin tests for the diagnosis of allergic reactions by applying various allergenic extracts to a patient’s skin. The device is sterile and must be disposed of after each use. The following procedure should be followed.

Step One: Prepare Device & Materials

• Set up the Multiple Well Test Tray and have ready access to a biohazard container. It is assumed that the physician has filled the tray wells with the suitable allergenic extracts prior to use in the test. See Figure 1.

• Open a package of sterile Skin Test Applicators and place an applicator in each of the test wells in the testing tray.