45.1 Putting the Pieces Together

While a presumptive diagnosis of allergic rhinitis (AR) can be made based on history and physical examination, testing for specific immunoglobulin E (IgE) antibodies to inhalant allergen(s) to which the patient reports symptoms helps confirm the diagnosis of AR and allows for potential treatment with immunotherapy. However to do this, several things are needed: a patient with symptoms consistent with allergy, specific allergy tests, and perhaps most importantly, a physician capable of interpreting the test results in light of the patient’s symptoms. Only if all of the above items are “checked off the list” is it likely that a correct allergy diagnosis will be made.

45.2 Serious Stuff

Proper evaluation and selection of which patients may benefit from skin testing is crucial.

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  Condition and reactivity of the skin can affect skin test results. Avoid skin testing patients with:

  
  
  
  
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    Dermatographism.

    
    
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    Diffuse urticaria.

    
    
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    Active dermatitis.

  
  
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  Proper selection of where the skin tests are to be placed is also important.

  
  
  
  
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    Skin pricks can be placed on the upper back or volar surface of the forearm.

    
    
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    The back is more reactive than the forearms.

    
    
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    Intradermals can be placed on upper arm.

    
    
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    Regardless of location, there needs to be sufficient space (about 2–2.5 cm) between each allergen applied.

    
    
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    Tests should not be placed in areas 5 cm from the wrist or 3 cm from the antecubital fossae.

  
  
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  Medications could alter the validity of the results. A large range of drugs may reduce skin reactivity and must be withheld before skin testing including:

  
  
  
  
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    First-generation and second-generation antihistamines

    
    
    
    
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       This includes eyedrops and nasal spray preparations.

       
       
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       The duration of suppression of skin test reactivity is variable between different drugs and individuals.

    
    
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    Antidepressants such as doxepin and other tricyclics have antihistamine activity.

    
    
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    Over-the-counter (OTC) preparations such as cold and flu remedies, “sinus” analgesics, antitussives, H2 blockers, etc., can affect skin response.

    
    
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    Herbal products have the potential to affect skin test results.

    
    
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    Antiemetics, sedatives, and muscle relaxants can also affect skin response.

    
    
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    Short-term oral corticosteroids do not significantly diminish the skin test reaction but may with prolonged use.

    
    
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    Prolonged topical corticosteroids have been shown to reduce skin reactivity.

    
    
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    Omalizumab can suppress skin reactivity.

  
  
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  Special class of medication:

  
  
  
  
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    Beta blockers are a risk factor for more serious and treatment-resistant anaphylaxis, making the use of beta blockers a relative contraindication to inhalant skin testing.

  
  
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  Relative contraindications/precautions:

  
  
  
  
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    Poor subject cooperation.

    
    
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    Patients unable to cease antihistamines or other medications.

    
    
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    Persistent severe/unstable asthma.

    
    
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    Pregnancy.

Proper selection of which patients may benefit from immunotherapy is paramount to good outcomes with immunotherapy.

Allergen immunotherapy should be considered for patients who have evidence of specific IgE antibodies to clinically relevant allergens demonstrated either through skin testing or in vitro specific IgE testing. The commitment to begin allergen immunotherapy is a shared decision between the physician and the patient after reviewing the patient’s response to medical management, including adverse effects of medications, response to avoidance measures, likelihood of adherence to an immunotherapy schedule, and patient preference. The severity and duration of symptoms along with effect on the patient’s quality of life should also be considered when assessing the need to proceed with immunotherapy.