Allergy refers to conditions in which immune responses to environmental
antigens cause tissue inflammation and organ dysfunction. Allergy testing is
performed to determine immunologic sensitivity or reaction to antigens for the
purpose of identifying the cause of the allergic state. This policy addresses
immediate (IgE-mediated) hypersensitivity and delayed (cell mediated)
hypersensitivity. In vivo allergy sensitivity testing correlates the
performance and evaluation of selective cutaneous and mucous membrane tests
with the patient's history, physical examination, and other observations.
Immediate hypersensitivity may also be tested in vitro by measurement of
allergen-specific serum IgE. Under certain limited conditions, this is covered
by Medicare Part B. Immediate hypersensitivity skin testing is important in
the diagnosis of IgE mediated inhalant, food, venom; and penicillin allergies,
delayed hypersensitivity testing is more often helpful in the diagnosis of
contact dermatitis and the clinical evaluation of cell-mediated immunity.  
  
**INDICATIONS**  
  
Allergy testing is allowed when it has proven efficacy as demonstrated through
scientifically valid peer reviewed published medical studies.

  * A complete medical and immunologic history and appropriate physical examination must be done prior to performing diagnostic testing.
  * The testing must be performed based on this history and a physical exam, which documents that the antigen being used for testing exists with a reasonable probability of exposure in the patient's environment.
  * It would not be expected that all patients would receive the same tests or the same number of sensitivity tests. The number of tests performed must be judicious and related to the history, physical findings, and clinical judgment specific to each individual.

  
**General Information**  
  
In vivo immunologic tests have been shown to be reliable and valid diagnostic
tools and include skin tests with standardized allergenic extracts by prick,
puncture, and intradermal techniques, skin end-point titration, and patch
testing.

  * **Percutaneous Testing** remains the test of choice in most clinical situations where immediate hypersensitivity reactions are suspected. Percutaneous tests require medical supervision, since there is a small but significant risk of anaphylaxis. Overall, skin testing is quick, safe, and cost-effective.
  * **Intracutaneous/Intradermal Tests** are usually performed when increased sensitivity is the main goal such as when percutaneous tests are negative and there is a strong suspicion of allergen sensitivity. The usual testing program may include 2 concentrations of an extract: a weaker concentration and a stronger concentration. It would not be expected that 3 or more concentrations of one extract would be medically necessary.
  * **Skin End Point Titration Testing** analyzes the highest dilution of a substance that produces a reaction, and may be used to determine the starting dose(s) of allergen immunotherapy.
  * **Delayed Hypersensitivity Skin Testing** has been commonly used in three ways: anergy testing, testing for infection with intracellular pathogens, and testing for sensitivity to contact allergens. Accurate testing for contact allergy requires careful attention to technique, and limitation of testing to the specific allergens known to be associated with a contact reaction.
  * **Photo Testing** is skin irradiation with a specific range of ultraviolet light. Photo tests are performed for the evaluation of photosensitivity disorders.
  * **Patch Testing** is indicated to evaluate a nonspecific dermatitis, allergic contact dermatitis, pruritus, and other dermatitis to determine the causative antigen.
  * **Photo Patch Testing** uses two patches, with one of them being irradiated with ultraviolet light half way through the occlusive period. It is indicated to evaluate unique allergies resulting from light exposure.
  * **Ophthalmic Mucous Membrane Tests and Direct Nasal Mucous Membrane Tests** are rarely indicated. They are allowed when skin testing cannot test allergens.
  * **Inhalation Bronchial Challenge Testing** involves the inhalation of agents that can trigger respiratory responses. The agents include drugs that cause airway constriction, antigens and chemical sensitizers usually related to occupational breathing problems. Pulmonary function studies are not included in the bronchial challenge test. Generally three measures of each determination (e.g., spirometry, prolonged post exposure evaluation of bronchospasm) are performed. The best of the three is accepted and represents one unit of service. A unit is defined as each set of three measurements.
  * **Ingestion Challenge Test** involves the administration of sequentially or incrementally larger doses of the test item. The test items may include food or antibiotics. The service is allowed once per patient encounter, regardless of the number of items tested, and includes evaluation of the patient's response to the test items.

  
**LIMITATIONS**

  * **Ingestion challenge food testing** performed by the patient in the home, and not in the office setting, will not be covered.
  * **Provocative testing** will be denied as not medically necessary.
  * **Quantitative or semi-quantitative in vitro allergen specific IgE testing** is covered under conditions where skin testing is not possible or is not reliable. In vitro testing is covered as a SUBSTITUTE for skin testing; it is usually not necessary in addition to skin testing. The number of tests done, frequency of retesting and other coverage issues, are the same as for skin testing. The indications for using in vitro testing instead of in vivo methods must be documented with the claim.
  * **Qualitative multiallergen screens for allergen specific IgE** have insufficient literature to support clear-cut clinical utility and will be denied as not medically necessary.

  
  
**Examples of indications for in vitro testing include the following:**

  * Patients with severe dermatographism, ichthyosis or generalized eczema;
  * Patients at increased risk for anaphylactic response to skin testing based on clinical history (e.g., when an unusual allergen is not available as a licensed skin test extract);
  * Patients unable to discontinue long-acting antihistamines, tricyclic antidepressants, or medications that may put the patient at undue risk if they are discontinued long enough to perform skin tests;
  * Patients with mental or physical impairments, who are uncooperative; or
  * Evaluation of cross-reactivity between insect venoms.

  
  
**The following are noncovered antigens:** newsprint, tobacco smoke,
dandelion, orris root, phenol, alcohol, sugar, yeast, grain mill dust, soybean
dust (except when the patient has a known exposure to soybean dust such as a
food processing plant), honeysuckle, fiberglass, green tea, or chalk.