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Clinical Utility of Testing
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If the patient comes in the Spring or Fall, I know what they are allergic to—so why test?
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Can’t I just use total IgE as a screen? If not, why is it included in the profile?
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It often seems like avoidance measures don’t work—how can I use this test to help improve symptoms?
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What is the role of the ImmunoCAP Specific IgE blood test in managing asthma?
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Do patients need to stop taking medications in order to be tested?
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What do I do when the results are positive/abnormal (ie, patient is allergic)?
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What do I do with a negative/normal test result (the patient is not allergic)?
A good history and physical is all I need to diagnose a patient’s allergies, so why would I want to order the test?
A: We’ve all been trained to think of history and physical together as the foundation of any diagnosis. But when evaluating a patient with suspected allergies, the clinician really needs a test to confirm or refute that diagnosis. Why? Because allergy-like symptoms can be a lot more difficult to diagnose than you may have thought. Many conditions (eg, allergic rhinitis, sinusitis, non-allergic rhinitis) can share the same symptoms of rhinorrhea, congestion, and increased secretions. Research indicates that, in allergies, history and physical alone yield a correct diagnosis only 50% of the time. My own experience bears this out. On more than one occasion, I’ve ordered the ImmunoCAP test thinking it would just confirm my suspicions, and I’ve been proven wrong. ImmunoCAP offers specific quantitative results that usually rule allergy in or out and, when positive, detail the patient’s allergic sensitivities. With these results I can employ avoidance measures, which may help to decrease the need for medications. I never evaluate a patient without history and physical, but when I’m doing an allergy workup, I like having that additional objective evidence to help guide my diagnosis.
In patients with rhinorrhea, congestion, or other allergy-like symptoms, it’s very simple. I just try non-sedating antihistamines or leukotriene antagonists, and usually get some kind of relief. Why would I want to order a test?
A: Although common practice, empiric trial of medications is not always an effective way to manage a patient’s allergy-like symptoms. If the medication doesn’t work, a patient’s discomfort will linger. Also, symptom resolution doesn’t always mean that you’ve solved the real problem. It may mean that you’ve masked it. Delay in meaningful treatment (and prevention of subsequent symptoms) or mild symptom relief without targeting true disease etiology may lead to complications or various sequelae (in the case of allergic rhinitis, these include sinusitis and otitis media). We also want to try and avoid exposing patients to the side effects of medications (such as antihistamines) that they may not need in the first place. In children with allergic disease, empiric treatment may yield some relief, but subclinical inflammation can persist—and promote continuation of the Allergy March. In addition, in patients young and old, incomplete resolution of inflammation in the upper airway is associated with asthma exacerbations. I like to pinpoint the underlying cause—and target it with the appropriate medications—right from the get-go.
If the patient comes in the Spring or Fall, I know what they are allergic to—so why test?
A: The seasonal nature of symptoms clearly points to allergy. The culprit may be not only ragweed or hayfever; it may also be one or two perennial allergens. Patients are often polysensitized, and allergy is a cumulative threshold disease, meaning that patients may have allergic sensitivities but will experience symptoms only after their personal allergic threshold load has been reached. By identifying all of a patient’s specific sensitivities, you may be able to reduce or avoid symptoms by controlling one or more of the perennial allergens to reduce that overall load.
I’m getting pushback from the local allergist, who says this test is unreliable. Should I really be doing allergy testing?
A: Absolutely. Contrary to what the allergist may think, ImmunoCAP Specific IgE testing is exceedingly reliable. FDA-cleared, it employs cutting-edge specific IgE assay technology that is far advanced beyond older, less reliable tests, such as RAST™. ImmunoCAP has been widely analyzed and validated, and many allergy experts consider the accuracy of its results to be highly reproducible and comparable to those offered by skin-prick testing. The pre-selected profiles have been engineered to detect more than 95% of patients with allergies. When speaking with allergists in my area, I simply tell them that the test has helped me greatly in managing my patients’ allergy-like symptoms. When the results are negative, I focus on possible non-allergic causes. When positive, I can use the specific quantitative results to aid treatment. Moreover, the ImmunoCAP results help me to target my referrals to an appropriate specialist. If I refer an allergic patient to an allergist, the ImmunoCAP results help the allergist to hit the ground running, to quickly conduct any additional testing that may be required or begin specialized treatments.
What do specialists think of ImmunoCAP?
A: As you might suspect, some local practicing allergists question the use of ImmunoCAP by primary care clinicians. Mistaking it for RAST and other older allergy assays, they assume it to be inaccurate and unreliable. They may also perceive its use to be in conflict with their provision of skin-prick testing. Nevertheless, a number of renowned allergy experts have embraced ImmunoCAP as a highly accurate assay and a valuable clinical tool. I know that, in my area, some allergists have come to accept the use of this technology in primary care as a valuable complement to their efforts.
Can’t I just use total IgE as a screen? If not, why is it included in the profile?
A: As a stand-alone test, total IgE is not very reliable. It lacks sensitivity as a rule-out screen. A patient’s specific IgE levels (the most reliable measure of allergic sensitization) may be high when total IgE is low or normal. Total IgE is included in ImmunoCAP profiles because there are occasions when it will be elevated without any specific IgE readings, indicating the need for additional allergy testing. In addition, extremely high total IgE may be seen in some very uncommon non-atopic conditions, which might warrant further investigation.
It often seems like avoidance measures don’t work—how can I use this test to help improve symptoms?
A: The ImmunoCAP Specific IgE blood test can be very helpful in guiding environmental control measures. The quantitative results reported by ImmunoCAP detail the degree of sensitivity to specific allergens, thereby guiding you to which allergen or allergens to target. In addition, patients are often polysensitized, and allergy is a cumulative threshold disease, meaning that patients may have allergic sensitivities but will experience symptoms only after their personal allergic threshold load has been reached. By identifying all of a patient’s specific sensitivities, you may be able to reduce or avoid symptoms by controlling one or more of the perennial allergens to reduce that overall load. If this is not successful, then targeted pharmacotherapy is the next step. In addition, immunotherapy can be an important means of long-lasting protection from airborne allergens.
Why should I incorporate this test into my practice? And what difference will it make in how I treat/manage my patients?
A: When we see patients with symptoms such as congestion, increased secretions, and rhinorrhea, it’s pretty easy to deduce that they’re caused by allergy. But the cause of these symptoms may also be vasomotor, viral or bacterial infection, or a number of other disorders. You could treat the symptoms, but making a definitive diagnosis is essential to determining appropriate treatment. Then you can ensure appropriate use of antibiotics, antihistamines, leukotriene antagonists, and intranasal steroids, which can result in fewer repeat office visits, fewer unnecessary referrals, and better outcomes. Since I’ve started using ImmunoCAP, I have found it’s really enhanced my practice of medicine and improved the overall satisfaction of my patients who suffer with these symptoms.
In adults, who should be tested?
A: While anyone presenting with nasal or other allergy-like symptoms is a candidate for specific IgE testing, it is not likely that everyone with rhinorrhea needs the test. Following a complete physical exam and review of the patient history, I generally consider using the ImmunoCAP Specific IgE blood test for patients with recurrent or chronic URD symptoms, ie, nasal congestion, rhinorrhea, increased secretions, or those patients who have failed on previous medications (including over-the-counter products). And of course, since allergies play such a major role in asthma, I always order an ImmunoCAP for my patients with confirmed asthma.
What is the role of the ImmunoCAP Specific IgE blood test in diagnosing and managing common upper respiratory diseases?
A: ImmunoCAP gives me objective quantitative evidence of atopy. I find it helpful because in patients with upper respiratory disease, symptoms such as congestion, rhinorrhea, and increased secretions overlap between allergic and non-allergic illnesses. An accurate differential diagnosis is important to guide management of these diseases, and history and physical used alone accurately diagnose allergic disease only about 50% of the time. I use an ImmunoCAP respiratory profile, along with the history and physical, to get to the true cause of the symptoms. With the results, I can rule atopy in or out and, if positive, focus on patient education, avoidance measures, and targeted allergy-based treatments like antihistamines or leukotriene antagonists. If the results are negative, I can focus on other possible symptom causes (hormonal, vasomotor, or infections), and avoid wasting the patient’s time and money on prescription antihistamines or leukotriene antagonists like Singulair®, which aren’t indicated if the patient isn’t allergic.
What is the role of the ImmunoCAP Specific IgE blood test in managing asthma?
A: Well over half of all people with asthma suffer from allergic triggers. These patients will have one or more allergic sensitivities that will trigger an exacerbation. I regularly use the ImmunoCAP test on my asthmatic patients to determine whether or not they are allergic and then, when they are allergic, to identify the specific triggers. This greatly aids in patient education and counseling for environmental control. Asthma management guidelines from the National Institutes of Health and other major organizations strongly endorse allergy testing and effective control of allergies as a key component of effective asthma management. I find that the ImmunoCAP test greatly aids my efforts to provide optimal care to my asthma patients.
Do patients need to stop taking medications in order to be tested?
A: No. The ImmunoCAP Specific IgE blood test quantitatively measures immunoglobulin E. Unlike skin testing, the assay is not influenced by medications. I find that it really makes things convenient, too. If a patient has upper respiratory symptoms, he or she may continue on meds while we await the test results, which can save them the distress that they may feel about stopping their medications. And it doesn’t matter what the patient is taking. Antidepressants, decongestants, and antihistamines won’t affect the accuracy of results. In fact, I just read an exciting study by Robert Hamilton of Johns Hopkins showing that even omalizumab, a therapy that directly targets serum levels of free IgE, does not affect the accuracy of ImmunoCAP test results.
What do I do when the results are positive/abnormal (ie, patient is allergic)?
A: When the results are positive, the ImmunoCAP test report spells out the patient’s specific allergies and the degree of sensitivity to each allergen. Allergy is a cumulative threshold disease, meaning that symptoms are often triggered only after exposure to multiple allergens. The patient who is sensitized to more than one allergen shows symptoms only after a cumulative allergic load has been reached. He or she can find resolution of symptoms through the avoidance of one or more allergens in order to diminish that cumulative load to a level at which symptoms don’t occur. I use the specific quantitative results from the ImmunoCAP test report as a discussion aid to offer proof of a patient’s (or child’s) allergic status, to aid management compliance or offer reassurance that a cause has been identified. I also use the results as detailed guide to effective management. They help me tailor the patient’s environmental control measures to reduce cumulative allergic load, and to select the right medications or referral, if necessary. When a patient is highly allergic, for instance, and has multiple environmental triggers, then referral to an allergist is a strong option clearly indicated by the evidence.
What do I do with a negative/normal test result (the patient is not allergic)?
A: I find that specific IgE testing offers great advantages when atopy is not involved. By ruling out an allergic etiology, I can focus on other possible causes (including anatomical, bacterial, medical, hormonal, and vasomotor). This way, I can pick the right treatments or make any necessary referrals. In addition, I avoid prescribing costly non-sedating antihistamines or even leukotriene antagonists (Singulair), which are generally thought to be ineffective and are not indicated for use in non-atopic disease.
Can I use the results to perform immunotherapy treatments?
A: The results reported by ImmunoCAP are quantitative and specific, and could be used to guide immunotherapy. However, sensitivity to an expanded number of allergens (beyond those offered in the pre-selected profiles) should be assessed before preparing individual prescriptions. Furthermore, due to a risk of severe systemic reactions, immunotherapy should be administered by a specialist in a setting equipped to handle medical emergencies.
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