Over 70 million Americans suffer from chronic nasal symptoms like congestion, runny nose, post-nasal drip, and sneezing.
Why is testing for allergies important? Over 70 million Americans suffer from chronic nasal symptoms like congestion, runny nose, post-nasal drip, and sneezing. These symptoms can be caused by various factors — allergies being one of them. The societal cost of allergies is substantial, not only because of how many people suffer from the disease but also because of the associated loss of productivity. The World Allergy Organization (WAO) estimates that 10-40% of the world's population suffers from allergies.¹ The economic costs of this can amount to more than $245 billion in the US.
The reason testing is so important is to conclusively determine if allergies are, in fact, the major trigger, or if a patient is suffering from something called non-allergic rhinitis. Allergic and non-allergic rhinitis have very similar symptoms and are difficult to differentiate based on symptoms alone. Ultimately, diagnosing allergies as soon as possible can help millions of people and save billions of dollars.
Today, many allergy tests exist including skin, oral, nasal, blood, and provocation tests. Different types of allergy testing can show different results, even for the same individual. It’s also important to note that allergies can change over time and that testing performed several years ago may be quite different from what we see today.
Below, we outline the advantages and disadvantages of each kind of allergy test.
Skin-Prick Tests (SPT) Skin-prick tests (SPT) are widely performed to help diagnose environmental allergies because of their simplicity, safety, and convenience. They work by introducing small quantities of the suspected allergen underneath the skin. A patient is considered sensitized if the wheal (pale, swollen bump) is at least 3 millimeters in diameter in response to a prick with the allergen of concern.
While this test does have its advantages, it’s not without limitations. Due to a lack of standardization, much of the accuracy of SPTs depends on the individual clinician’s technique and interpretation. There is also decreased accuracy if a patient is taking antihistamines, certain antidepressants, or immunosuppressants when they do the test[4].
Intradermal Tests (IDT) IDTs can be used if there is high suspicion for a specific allergen following a negative skin-prick test. Similar to SPTs, doctors introduce allergens into the skin (but deeper into the dermis) to assess immune response. While IDT is the most sensitive skin test when testing for environmental allergies, it has a lower specificity than SPT, which means that it can often lead to false positive results.
Patch Test This is a popular test for patients suffering from contact dermatitis, such as the development of a localized rash many people get from nickel. Doctors test for allergies by placing the suspected allergens on patches that are placed onto the skin (usually the upper back) and assessing the skin at the site of each patch for a reaction on three separate occasions within a week. This test is low risk and easy to perform but it requires multiple visits to the doctor's office, interpreting the results requires specialized training and it is often only available in specialized centers.
Blood Tests
1. Serum Allergen-Specific IgE Concentrations
This test measures the levels of specific IgE antibodies against various allergens in the blood. If you have allergies, you may have more specific IgE in your blood than usual. It’s often considered comparable to SPT and may be preferred in situations where SPT can’t be performed either due to overly sensitive skin or when a patient cannot come off a certain medication which can affect testing results (e.g. antihistamines, select antidepressants, etc.).
2. Basophil Activation Test (BAT)
While mainly found in research settings, the basophil activation test (BAT) is used to evaluate allergies when other tests have been inconclusive. During the test, experts incubate patients' blood with a suspected allergen and monitor basophil activity. Due to the technical complexity of the test itself, the utilization of BAT remains very limited despite good preliminary results for both food and drug allergy detection.
So, which allergy test should I take? Today, many allergy tests exist. They have varying detection rates, ease of use, and benefits. However, both skin testing and blood allergy testing are likely to identify the most clinically important allergens. Nectar’s at-home allergy testing is CLIA-certified, globally used, and designed to test the most important environmental allergens across the US.
The best diagnosis comes from a thorough review of all available data including a patient’s clinical history, geographic location, and all the allergy tests they’ve ever taken.
What happens after I get tested? If you test positive for allergies, a licensed provider will determine what can be treated with allergy immunotherapy. If eligible for immunotherapy, they will create a custom formula that takes into account your clinical history, geographic location, and test results. This formulation includes therapeutic levels of the two most important allergens as studies have shown this protocol provides symptom relief across the board.
If your allergy test does not detect allergies, you're not alone. 30-50% of patients who struggle with allergy-like symptoms suffer from non-allergic rhinitis. Fortunately, there are treatments that can help relieve these symptoms. Nectar is here to help you make sense of your results and to provide the best possible path forward.
Citations:
¹ R. Pawankar, “Allergic diseases and asthma: a global public health concern and a call to action,” World Allergy Organ. J., vol. 7, no. 1, p. 12, 2014, doi: (http://paperpile.com/b/wf78qX/8F8j)10.1186/1939-4551-7-12. (http://dx.doi.org/10.1186/1939-4551-7-12.)
² M. L. Kowalski et al., “Risk and safety requirements for diagnostic and therapeutic procedures in allergology: World Allergy Organization Statement,” World Allergy Organ. J., vol. 9, no. 1, pp. 1–42, Oct. 2016, doi: (http://paperpile.com/b/wf78qX/U0L6)10.1186/s40413-016-0122-3. (http://dx.doi.org/10.1186/s40413-016-0122-3.)
³ I. F. Nevis, K. Binkley, and C. Kabali, “Diagnostic accuracy of skin-prick testing for allergic rhinitis: a systematic review and meta-analysis,” Allergy Asthma Clin. Immunol., vol. 12, p. 20, Apr. 2016, doi: (http://paperpile.com/b/wf78qX/tAYN)10.1186/s13223-016-0126-0. (http://dx.doi.org/10.1186/s13223-016-0126-0.)
⁴ “IgE allergy diagnostics and other relevant tests in allergy, a World Allergy Organization position paper,” World Allergy Organ. J., vol. 13, no. 2, p. 100080, Feb. 2020, doi: (http://paperpile.com/b/wf78qX/d4AZ)10.1016/j.waojou.2019.100080. (http://dx.doi.org/10.1016/j.waojou.2019.100080.)
⁵ L. Heinzerling et al., “The skin prick test - European standards,” Clin. Transl. Allergy, vol. 3, no. 1, Feb. 2013, doi: (http://paperpile.com/b/wf78qX/dF7O)10.1186/2045-7022-3-3. (http://dx.doi.org/10.1186/2045-7022-3-3.)
⁷ A. Barbaud et al., “Intradermal Tests With Drugs: An Approach to Standardization,” Front. Med., vol. 7, p. 156, May 2020, doi: (http://paperpile.com/b/wf78qX/ahrY)10.3389/fmed.2020.00156. (http://dx.doi.org/10.3389/fmed.2020.00156.)
⁹ R. Lazzarini, I. Duarte, and A. L. Ferreira, “Patch tests,” An. Bras. Dermatol., vol. 88, no. 6, Nov. 2013, doi: (http://paperpile.com/b/wf78qX/1iRX)10.1590/abd1806-4841.20132323. (http://dx.doi.org/10.1590/abd1806-4841.20132323.)
¹⁰ “Designing Predictive Models for Beta-Lactam Allergy Using the Drug Allergy and Hypersensitivity Database,” J. Allergy Clin. Immunol. Pract., vol. 6, no. 1, pp. 139–148.e2, Jan. 2018, doi: (http://paperpile.com/b/wf78qX/Suzv)10.1016/j.jaip.2017.04.045. (http://dx.doi.org/10.1016/j.jaip.2017.04.045.)
¹² M. Calvani, A. Bianchi, C. Reginelli, M. Peresso, and A. Testa, “Oral Food Challenge,” Medicina, vol. 55, no. 10, Oct. 2019, doi: (http://paperpile.com/b/wf78qX/q9Cg)10.3390/medicina55100651. (http://dx.doi.org/10.3390/medicina55100651.)
¹³ G. K. Ziade et al., “Reliability assessment of the endoscopic examination in patients with allergic rhinitis,” Allergy Rhinol. , vol. 7, no. 3, Jan. 2016, doi: (http://paperpile.com/b/wf78qX/Cmj7)10.2500/ar.2016.7.0176. (http://dx.doi.org/10.2500/ar.2016.7.0176.)
¹⁴ P. Singhvi, N. Baisakhiya, and G. Singh, “Study the Role of Nasal Scrap Cytology in Allergic Rhinitis Patients in Rural Population,” Indian J. Otolaryngol. Head Neck Surg., vol. 71, no. Suppl 3, p. 2057, Nov. 2019, doi: (http://paperpile.com/b/wf78qX/gbJv)10.1007/s12070-018-1468-3. (http://dx.doi.org/10.1007/s12070-018-1468-3.)
¹⁵ R. I. Siles and F. H. Hsieh, “Allergy blood testing: A practical guide for clinicians,” Cleve. Clin. J. Med., vol. 78, no. 9, Sep. 2011, doi: (http://paperpile.com/b/wf78qX/F8rs)10.3949/ccjm.78a.11023. (http://dx.doi.org/10.3949/ccjm.78a.11023.)
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