Allergy Diagnostic Testing

Jurisdiction: J15 MAC Part B. States: Kentucky, Ohio. Type: Active LCD

Overview Allergy is a hyper-immunologic response to environmental substances, known as allergens, that commonly affect organs such as the skin, eyes, ears, nose, throat, and GI tract. 1-4 An allergen is an antigenic substance that triggers this immune response. 5 A Type I Hypersensitivity reaction is the primary mechanism driven by immunoglobulin E (IgE) antibodies. These antibodies activate mast cells and basophils which release histamine and other pro-inflammatory mediators upon encountering the allergen. 1,3,4,6,7 Symptoms can include itchy, watery eyes, sneezing, coughing, skin redness, local or wide-spread hives (urticaria), asthma, angioedema, vomiting, diarrhea, and in severe cases, anaphylaxis. 1,8,9 In some cases, allergens can also cause a Type IV Hypersensitivity reaction, which is delayed and mediated by chemical messengers (cytokines) released by sensitized helper T cells. 4,10,11 Allergic reactions vary from person to person, and not everyone reacts to allergens in the same way. Therefore, when symptoms are significant, diagnostic testing may be necessary to identify the specific allergen(s) and guide treatment. This policy addresses both immediate IgE-mediated hypersensitivity reactions and delayed cell mediated hypersensitivity. It includes guidelines for in vivo testing (such as skin tests), organ challenge tests, serum specific IgE in vitro testing, and details on limitations and provider qualifications. Coverage Indications Indications for Allergy testing Allergic diagnostic testing is generally divided into 2 main types: In Vivo and In Vitro testing. Allergy testing is covered when it has proven efficacy as demonstrated through scientifically valid peer reviewed published medical studies. A comprehensive medical and immunologic history and physical examination with testing based on reasonable exposure to the suspected allergen(s) should be demonstrated in the documentation to support reasonable and necessary coverage requirements. Unrelated multi-allergen panels are not considered reasonable and necessary. Due to the possibility of unforeseen severe allergic reactions medical supervision and resuscitative equipment must be available during in vivo testing. In Vivo Testing In vivo testing includes various skin tests to diagnose allergic reactions. Findings must be correlated with clinical symptoms. The use of positive and negative controls is required. Percutaneous Testing - commonly used for suspected IgE-mediated allergic reactions to inhalants, Hymenoptera venoms (wasps, honeybees, yellow jackets, hornets, imported fire ants, and others), foods, and certain drugs and occupational Intracutaneous/Intradermal Testing (IDT) - used when percutaneous tests are negative, yet suspicion remains high. Not recommended for food or latex allergy due to risk of systemic reactions. Skin Endpoint Titration (SET) Testing (also known as Intradermal Dilutional Testing)- used to determine immunotherapy starting doses for primarily Hymenoptera venom or aeroallergen sensitivities. Skin Patch Testing - used for diagnosis of allergic contact dermatitis (ACD) caused by various substances (e.g., detergents, oils, metals, drugs, chemicals, food products). Custom patch testing may be needed based on clinical history. Photo Patch Testing- used if exposure to allergens is suspected to be worsened with UV light. Photo Testing- involves skin irradiation with UV light to evaluate photosensitivity. Delayed Hypersensitivity Skin Testing - commonly used for testing contact allergens (see skin patch testing) and infections with intracellular pathogens (such as tuberculin), or anergy tests. Organ Challenge Testing/Allergen Provocation Testing : Further in vivo testing via organ challenge is reserved for cases where clinical history suggests allergy, but initial skin or serum IgE testing is inconclusive. Testing should be performed in a clinical setting in which immediate emergent response by the physician and/or clinical staff is readily available. Testing should be performed in a double-blinded, if not single-blinded fashion. Nasal Mucous Membrane Challenge Tests- Confirms the cause of allergic rhinitis Ophthalmic Mucous Membrane (Conjunctival) Challenge Tests- Assesses localized eye symptoms in the diagnosis of allergic conjunctivitis and may assist in the diagnosis of allergic rhinitis. Inhalation/Bronchial Challenge Test: Measures airway hyperresponsiveness, often used in asthma cases. Must be measured objectively, compared with a placebo control, usually involving some form of pulmonary function testing(e.g., measurement of FEV 1 before and after introduction of suspected allergen). Generally, 3 measures of each determination (e.g., spirometry, prolonged post exposure evaluation of bronchospasm) are performed. The best of the 3 is accepted and represents 1 unit of service. A unit is defined as each set of 3 measurements. Pulmonary function studies are not included in the bronchial challenge test. Oral Challenge Test: Administers food or drug allergens in increasing doses to monitor reactions. 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. Oral challenge is not payable when used to diagnose rheumatoid arthritis, depression, or respiratory disorder. Please refer to CMS Pub. 100-03, Medicare National Coverage Determinations (NCD) Manual , Chapter 1, Part 2, Section 110.12 for additional coverage details. Food Challenge Test: Considered reasonable and necessary for the following indications: food allergy, anaphylactic shock due to an adverse food reaction, and suspected food related dermatitis. It is Noridian's expectation that the need for oral food challenge (OFC) would stem from non-confirmatory results after having performed more commonly utilized first line in vivo testing such as skin prick testing (SPT) or patch testing; or in vitro testing such as serum food specific IgE testing, unless testing for suspected allergen is not readily available. OFC testing is discontinued if objective reactions are identified, or the last dose of food tested does not elicit any reactive systems. Testing performed by the patient in the home, and not in the office setting under medical supervision, will not be covered. Drug Challenge Testing : Gradual administration of suspected drug allergens under close medical supervision. Used in the diagnosis of suspected IgE mediated drug allergy, especially drugs such as nonsteroid anti-inflammatory drugs (NSAIDs), local anesthetics, non-beta lactam antibiotics, and other medications. Testing should only be performed when no alternative diagnostic method is available and/or there is no equally effective drug substitution. It is Noridian's expectation that the need for oral drug challenge would stem from non-confirmatory results after having performed more commonly utilized first line in vivo testing such as SPT or patch testing; or in vitro testing such as serum IgE testing, unless testing for suspected allergen is not readily available. In Vitro Testing Immunoassays measuring serum IgE levels are an alternative diagnostic approach. Total Serum IgE : Covered for indications including: Follow up of Allergic bronchopulmonary aspergillosis (ABPA) Select immunodeficiency such as Hyper-IgE syndromes Eczematous dermatitis Recurrent Pyogenic infections Evaluation for omalizumab therapy in the treatment of moderate-to-severe allergic asthma Allergen Specific Serum IgE : Covered for indications including: Contraindications to skin testing secondary to widespread skin disease (e.g., dermatographism, ichthyosis, extensive dermatitis, generalized eczema) Medication use impacting skin testing results that cannot be safely discontinued (e.g., long-acting antihistamines, tricyclic antidepressants) Uncooperative patients secondary to age and/or mental and/or physical impairment Patients at significant risk of anaphylaxis Uncontrolled asthma Inconclusive skin testing results to rule out cross-reactivity and/or in setting of persistent clinical suspicion for allergy Limitations Inhalant allergy evaluation may require up to 70 percutaneous tests and up to 40 intracutaneous tests if percutaneous tests are negative. Patch tests may require up to 80 tests. Routine repeat skin testing is not considered reasonable and necessary unless documentation supports the need (e.g., changes in environmental exposure, new clinical signs/symptoms, lack of efficacy of current immunotherapy). The total number of tests, i.e. prick or intracutaneous, should not exceed generally accepted standards of testing set forth by professional associations. Exceeding these parameters may be justified if preliminary testing failed and immunotherapy failed to control symptoms. In this case, documentation of medical necessity is warranted. In-vitro testing performed in addition to skin testing for the same antigen is not usually necessary, except in the case of suspected latex sensitivity, Hymenoptera, or nut/peanut sensitivity where both the skin test and the in-vitro test may be performed. Allergy testing for substances such as newsprint, sugar, cornstarch, orris root, tobacco smoke, cotton, formaldehyde, and smog is not supported by evidence and hence is not covered. Payment for all serum lab testing requires performance in CLIA (Clinical Laboratory Improvement Amendments of 1988) certified laboratories. (42 CFR 493.3)