Diagnosis
Before a diagnosis of allergic disease can be confirmed, the other possible causes of the presenting symptoms should be carefully considered. Vasomotor rhinitis, for example, is one of many maladies that shares symptoms with allergic rhinitis, underscoring the need for professional differential diagnosis. Once a diagnosis of asthma, rhinitis, anaphylaxis, or other allergic disease has been made, there are several methods for discovering the causative agent of that allergy.
Effective management of allergic diseases relies on the ability to make an accurate diagnosis. Allergy testing can help confirm/rule out allergies and consequently reduce adverse reactions and limit unnecessary avoidance and medications. Correct diagnosis, counseling and avoidance advice based on valid allergy test results will help reduce the incidence of symptoms, medications and improve quality of life. For assessing the presence of allergen-specific IgE antibodies, you can use two different methods—a skin prick test or an allergy blood test. Both methods are recommended by the NIH guidelines and have similar diagnostic value in terms of sensitivity and specificity.
A healthcare provider can use the test results to identify the specific allergic triggers that may be contributing to the symptoms. Using this information, along with a physical examination and case history, the doctor can diagnose the cause of the symptoms and tailor treatments that will help the patient feel better. A negative result can help the doctor rule out allergies in order to consider other possible.
NIH Guidelines state that: “sIgE tests are useful for identifying foods potentially provoking IgE-mediated food-induced allergic reactions, and specified ‘‘cutoff’’ levels, defined as 95% predictive values, may be more predictive than skin prick tests of clinical reactivity in certain populations.” It further states, “sIgE tests are very useful for detecting the presence of sIgE antibodies, which indicates the presence of allergic sensitization. Fluorescence-labeled antibody assays have comparable sensitivity to that of skin prick tests, and the absolute levels of sIgE antibodies may directly correlate with the likelihood of clinical reactivity when compared with oral food challenges for the identification of foods provoking IgE mediated FA.”
According to NICE Guidelines, skin prick tests and blood tests are equally cost-effective and health economic evidence show that both the IgE antibody test and the skin prick test were cost effective compared with no test. Also, earlier and more accurate diagnoses save cost due to reduced GP consultations, referrals to secondary care, misdiagnosis and emergency admissions.
Allergy undergoes dynamic changes over time. Regular allergy testing of relevant allergens provides information on if and how patient management can be changed, in order to improve health and quality of life. Annual testing is often the practice for determining whether allergy to milk, egg, soy, and wheat have been outgrown and the testing interval is extended to 2 to 3 years for allergy to peanut, tree nuts, fish, and crustacean shellfish. Results of follow-up testing can guide decision-making regarding whether and when it is safe to introduce or re-introduce allergenic food into the diet.
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