The prevalence of food allergies has increased in recent decades. In fact, according to a 2013 study, that prevalence increased by 50 percent over a 12-year period.1 And with that prevalence has come fear. That’s because for many food allergy patients and their families, a systemic reaction is possible. And living with the possibility of such dire consequences results in anxiety, social isolation, and decreased quality of life.2
As a physician, I’ve seen many of these patients and witnessed their fear firsthand. It’s why I believe any tool that can help with the diagnosis and management of food allergies is one that should be used to its fullest extent. One such tool that has the power to drastically alter both diagnosis and management for food allergies is component testing.
What is component testing?
Although component testing for allergic sensitization is standard practice in Europe today,3 many healthcare providers in the U.S. are still unfamiliar. Simply put, specific IgE allergen component blood testing tells more of the allergy story than whole allergen testing alone. It examines the potentially offending allergens on the molecular level, so healthcare providers can determine which individual peanut proteins, for example, the patient is sensitized to.
Being able to identify the sensitizing components has significant diagnostic implications. Continuing with the peanut example, component blood testing for peanut can look at several peanut proteins, including Ara h 1, Ara h 2, Ara h 3, Ara h 6, Ara h 8, and Ara h 9. Sensitization to Ara h 1, 2, 3, and 6 reveals that the patient has a higher likelihood of having a systemic reaction when consuming peanuts. Sensitization to Ara h 8 is mainly associated with either no clinical reactivity or with isolated local reactions (E.g. food – pollen syndrome otherwise known as oral allergy syndrome).3
Thus, the component test results can let a healthcare provider know with some confidence whether or not the patient is a good candidate for an oral food challenge (OFC). Your patient is sensitized to Ara h 6, and at high risk for a systemic reaction? You might want to skip the OFC. They’re sensitized to Ara h 8 only? Not only does this suggest it’s safer to proceed with an OFC, but it can also put the patient’s mind at ease.
Allergen component blood testing is available for the following foods:
- Some tree nuts
Why you should be ordering with reflex
Unlike skin-prick testing, specific IgE blood testing allows you to order component results. And the fastest, easiest way to get those results is to order with reflex. There are many benefits:
- No need for a second blood draw. With reflex testing, a patient only has to have one blood draw to get comprehensive results of clinical significance. Instead of having one whole allergen blood test performed, waiting for the results, and having to come back in if the results warrant it, the phlebotomist need only draw a slightly higher volume of blood the first go-around. This saves the patient time and pain—it’s a win-win.
- Results tell you more of the story than whole allergen results alone. Reflex testing simply saves time for you and the patient. As I already mentioned, the results have significant diagnostic implications. If there’s a possibility of having access to this information, there’s no reason why you shouldn’t take advantage of it.
- Reflex only occurs when results are positive. Only if a whole allergen test indicates sensitization will the reflex occur.
There are some “downsides” to reflex testing, but in my opinion, they are countered by inherent benefit:
- Testing with reflex costs more. Yes, it’s true that by ordering with reflex, the overall cost of the test will be higher in the instances where a patient is sensitized to the whole allergen. But the information you gain from the test results more than justifies the cost. The additional cost is also not typically exorbitant; as a proxy for what an insured patient could reasonably expect to be billed, CMS reimburses $22.14 per component.4
- Some healthcare practitioners may find the results overwhelming. Testing with reflex produces component results, which can be overwhelming to the untrained eye. For some physicians who may be encountering this kind of information for the first time, they don’t understand how to communicate the meaning of the results, or fear burdening the patient with details that aren’t diagnostically relevant.
But as I’ve just discussed, the details are relevant. Luckily, there are training materials out there that can help guide physicians through the results. From detailing which results indicate that a patient is a good candidate for a baked egg or baked milk OFC, to which results indicate that a patient should stay away from a food altogether, these materials are extremely helpful.
- Jackson K et al. Trends in Allergic Conditions Among Children: United States, 1997-2011. National Center for Health Statistics Data Brief. 2013. Retrieved from https://www.cdc.gov/nchs/data/databriefs/db121.pdf
- Boyce, JA et al. Guidelines for the Diagnosis and Management of Food Allergy in the United States: Report of the NIAID-Sponsored Expert Panel. J Allergy Clin Immunol. 2010 December. 126(6 0): S1-58. Doi:10.1016/j.jaci.2010.10.007
- Matricardi, PM, et al. EAACI Molecular Allergology User’s Guide. Pediatr Allergy Immunol 2016: 27: (suppl23): 1–250.