Speaker: Communicate with patients to dispel myths about food allergy testing

Key takeaways:

• Blood tests identify sensitization, not allergies.
• Hair analysis, electrodermal testing and kinesiology have no utility.
• Physicians need to educate patients and families and be a resource.

BOSTON — Physicians should be prepared to bust some myths during discussions with families about food allergy testing, according to a presentation at the American College of Allergy, Asthma & Immunology Annual Scientific Meeting.

“Ultimately, it is our job to educate patients and families on myths, misconceptions and the true risks of their allergic conditions,” Amanda Michaud, DMSc, PA-C, AE-C, physician assistant at Family Allergy & Asthma Consultants in Jacksonville, Florida, said during her presentation.

Michaud, who also is a member of Healio’s Allergy/Asthma Peer Perspective Board, reminded physicians of their oath to first do no harm.

“A lot of things are done, not just in primary care pediatric clinics but also even in allergy clinics, that are against the guidelines and cause more harm than good,” she said. “We need to make sure we are doing things right by our patient, even though that might cause some difficult situations or discussions.”

When patients believe they have a food allergy, even though physicians know “in their hearts and minds” that it is not an IgE-mediated food allergy, physicians need to avoid being dismissive in addition to showing empathy, Michaud said.

“Patients do have strong belief systems, and sometimes this can be really challenging, and we don’t all have an hour to spend with some of our patients, unfortunately,” she said.

Say no to food panels

One common myth in food allergy is that blood tests will tell patients what they are allergic to, Michaud said.

“Sensitization or the presence of positive testing or serum specific IgE does not equal clinical allergy,” Michaud said. “There is no clinical indication to ever, ever, ever, ever, ever order a full food panel.”

Michaud conceded that this can be challenging since patients may have a lot of symptoms and are looking for help in navigating them, even though there are no clinical indications to order a food panel and testing is not diagnostic.

“In the absence of a clinical reaction, we need those reproducible clinical reactions with IgE-mediated type symptoms, as well as the testing that serves to confirm an already suspected diagnosis,” Michaud said. “History is the most important thing.”

Michaud also noted the impact of direct-to-consumer IgE panels available from corporate laboratories on patient perceptions.

“It’s awful that patients can go pay cash and order these tests without a provider actually giving them guidance or interpreting them with them,” she said.

“And of course, those results are reported in this range, these meaningless classes that mean absolutely nothing, and a giant, red, bold finding, and a big exclamation point accompanies any value that’s greater than 0.1 kU/L,” she continued.

Yet physicians know that these values are not truly clinically relevant for a lot of these foods, she said, even if they are 0.2 kU/L or 0.3 kU/L, and they could be considered false positives.

Michaud additionally cited research finding positive serum specific IgE for various foods among up to 15% of adults and 28% of children, with actual allergy rates ranging from 4% to 8%.

“There is harm in ordering full food panels,” she said. “This harm can include physical harm, psychological harm, financial costs, opportunity costs and health care disparities.”

Physical harm may occur when foods are eliminated from the diets of young children with eczema who may be at risk for sensitization through the skin barrier because of a positive test, and then these children lose tolerance to these foods.

“These little babies with eczema, they test positive for everything,” Michaud said. “When that food is removed from their diet, they will potentially be at risk of developing IgE-mediated reactions, including anaphylaxis.”

Nutritional deficiencies resulting from elimination diets are another risk, she said.

“There are literally cases of scurvy in food elimination cases, things that we really don’t and shouldn’t see in developed nations,” Michaud said.

Patients with true food allergy are at increased risk for bullying, anxiety and lower health-related quality of life, she continued. Financial costs may include additional health care visits with repeat serum IgE testing, skin prick testing, and oral food challenges in addition to autoinjector prescriptions. Alternative diets represent added costs too.

“You might have a younger child and you want to do a supervised feeding or challenge in the office,” Michaud said. “That costs money and time, as well as the cost for specialized diets.”

Opportunity costs include delayed introduction to suspected allergens, missing chances to prevent food allergy, and elimination of other foods that the child previously tolerated. Health care disparities also are a concern.

“We do see lower access to specialist care in some communities where these patients don’t have proper guidance and higher rates of sensitization among minorities, so it can disproportionately affect that population,” she said.

Communication is essential in guiding patients through these challenges, Michaud said.

“I do empathize with their symptoms and say, ‘Hey, I understand you’re having all these symptoms that you feel are related to a food.’ You’re validating their symptoms,” she said. “I like to tell them, ‘You know what? Our testing is great at helping when we have a high risk of anaphylaxis and those IgE-type symptoms.’”

Michaud then reviews those symptoms and tells her patients that she is happy that they are not experiencing them, but she adds that she is sorry that testing cannot help them.

“I explain to them that if we go fishing, we will find something, and it will not be truly indicative of their clinical allergy,” she said.

Other tests

Michaud further noted that no tests can reliably predict anaphylaxis.

“There are epitope tests and basal activation tests with studies ongoing that can help and maybe give us some more information here,” she said. “But no test can reliably predict a patient’s dose threshold for anaphylaxis.”

Also, she said, the severity of reactions does not always worsen with each exposure.

“That’s a big myth that we all hear a lot in our practice,” Michaud said. “‘My pediatrician said the next time little Johnny has a peanut he could die.’ That’s a whole other issue, but that is not a true reality for many of our patients.”

The size of the wheal in the SPT and the level of serum-specific IgE correlate with likelihood for true allergy, Michaud said, but not with potential severity. However, she added, allergists may use predictive values.

“These are reliable, in some cases, to help guide us if we do have a patient with known food allergy to when we’re considering introduction or an oral food challenge, or if a patient comes to us having a full food panel done,” she said.

“Predictive values can be very helpful at even helping explain away to patients and families, ‘Hey, this is why I’m not concerned. You don’t have these symptoms. But also look at your testing result. This isn’t even close to what we would consider maybe more diagnostic,’” she said. “This is a good tool that you can use in your practice.”

Patients may ask about other kinds of tests that have no diagnostic value as well, Michaud said, calling them “modern snake oil treatments.”

“We are trying to support our patients and give them some information about why these tests don’t work,” she said. “It’s the providers and clinicians that offer these therapies. They are the problem, and the companies that create them.”

Allergists need to talk to their patients about why these tests are not reliable instead of being dismissive of them, Michaud advised.

For example, most studies of IgG testing have been retrospective with subjective measures of improvement and flaws in their methodology, she said.

“IgG does not indicate allergy to a food, or intolerance, but merely indicates exposure to a food,” Michaud said. “And we know from some of our [oral immunotherapy] studies that as kids start to tolerate their allergen, their IgG actually increases because of that exposure.”

Also, Michaud said, there is no correlation between IgG and the positive results of double-blind placebo-controlled food challenges. But IgG testing can increase the likelihood of false diagnoses, unnecessary avoidance and reduced quality of life.

Alcat (Cell Science Systems) testing aims to measure changes in white blood cell volumes with exposures to certain foods and then identify foods that may trigger reactions. The results of these tests are then used to customize elimination or rotation diets to reduce what has been called “chronic immune system activation,” Michaud said.

“The term drives me nuts,” she said.

“Though there are changes in these white blood cell concentrations, there’s no evidence that’s actually pathologic,” Michaud continued. “There are unproven statements but no studies published in any peer reviewed journals showing any benefit.”

Patients and families also may ask about provocation or neutralization testing, when physicians inject increasing concentrations of food extracts into patients intradermally. When patients develop symptoms, they receive another dose to neutralize those symptoms.

“Double-blind studies show that they are no more likely to induce or alleviate symptoms compared to saline,” Michaud said. “In fact, 70% of patients in one study reported subjective symptoms to saline injection.”

But patients with true IgE allergies may develop systemic reactions.

“First, do no harm,” Michaud said. “I wish that applied to the people that did these tests, because clearly it doesn’t.”

Also, hair analysis is “not a thing,” Michaud said, with no published studies indicating that it works.

“Researchers have sent the same sample to various labs, sometimes the same sample to the same lab, and gotten completely different results and no correlation of symptoms,” she said.

Electrodermal testing is another technique with no diagnostic value, Michaud said. Patients hold an electrode in one hand as another electrode is placed elsewhere on their body. There also is a glass vial that includes the suspected allergen in the electrical circuit.

If there are any changes in skin impedance, which is measured in arbitrary units, the patient is deemed allergic.

“We all know that doesn’t make any sense,” Michaud said. “It’s just so ridiculous that this is something that’s actually done.”

Double-blind studies have shown that electrodermal testing has no utility, she continued, with no reproducibility between histamine, allergens and saline and 25% of all tests indicating positive results anyway.

Finally, Michaud said that kinesiology muscle testing probably was the second most common questionable test offered in her community, after IgG testing.

Patients hold a vial with the tested food in one hand and extend their other hand. The provider puts downward pressure on the extended arm. If the arm seems weak, the provider says the patient is sensitized to the food.

“I just, I can’t,” Michaud said. “I can’t even.”

Communication is key

“It’s our job to help educate these patients and families and serve as a good resource for them. I like to tell my families I understand these companies are preying on you,” Michaud said.

While patients experience a variety of symptoms, these companies claim that they are going to alleviate and fix them while comforting patients with a test or diagnosis that explains their issues, she continued.

“I understand that and empathize with them,” Michaud said. “But it’s important that we also, rather than being dismissive, really empathize with them and try our best to help them.”

For more information:

Amanda Michaud, DMSc, PA-C, AE-C, can be reached by email at amandalmichaud@gmail.com or on Twitter @theallergypac.