“Primary care doctors often use the wrong test to diagnose food allergies in children, new research shows.” - Reuters
Dr. Dave Stukus conducted that new research and in an Interview on Henry Erlich’s blog on the Asthma Allergies Children website, Dr. Dave further explained why he did the study:
“…The idea for this study originated from patients being seen in our office every day. We routinely receive referrals for evaluation of suspected food allergies in infants and young children, many of whom already had serum IgE testing performed. Sometimes they have foods taken out of their diet based upon these results. Many times, parents are told to withhold introduction of new foods based upon these tests. Rarely, we see patients develop a new allergy to a food they were eating regularly without problems but produced IgE towards; the food is removed based upon testing and then, when reintroduced weeks or months later, they develop a new allergic reaction to that same food they were previously eating without problems. So, yes – this felt like it was a big problem but had not previously been objectively assessed or characterized on a wide scale, which is what we sought to do.”
You can read more of that excellent interview here.
You can read more of that excellent interview here.
You can also read about food allergies and testing here on Huff Po.
I had a chance to interview Dr Dave about his study in Pediatrics: Use of Food Allergy Panels by Pediatric Care Providers Compared With Allergists. Read more below.
An individual walks into their doctor’s office and says I think I have a food allergy. What *should * happen next?
If someone suspects they have a food allergy, they should first discuss with their primary doctor. Many patients may request testing or feel their symptoms are due to an allergy, but there are a lot of questions/details that need to be asked before any type of testing should be performed. My advice to anyone concerned about food allergy: discuss with your doctor and be prepared for lots of questions! This is essential in trying to figure out the best diagnosis. If, after that discussion, you have ongoing concerns or a food allergy diagnosis seems likely, then allergists can be extremely helpful.
However, regardless, first and foremost, a detailed, thorough history should be obtained. The first step in diagnosing a food allergy is being thoughtful about the patient’s concerns, including the specific foods they are worried about, their symptoms, the timing of symptom onset, symptom duration, and reproducibility of symptoms. When it comes to food allergies, milk, egg, wheat, soy, peanuts, tree nuts, fish and shellfish account for up to 90% of all reactions. Any food can cause a food allergy, but fruits and vegetables are unlikely causes of IgE-mediated allergic reactions.
Many people may experience any number of adverse reactions after ingestion of a food, but food allergy reactions occur pretty fast (within minutes or 1-2 hours later), occur with every ingestion regardless of form; if someone is allergic to milk for instance, then they will have symptoms after eating cheese, yogurt, ice cream, etc. And have objective symptoms such as hives, swelling, wheezing, and vomiting.
Sometimes when a patient explains their history it becomes clear that their history is more consistent with a non-allergic intolerance, such as difficulty digesting lactose, which can cause bloating and stomach pains, for example. Sometimes the history reveals chronic conditions such as heartburn or inflammatory bowel disease as more likely culprits but none of those are food allergy symptoms.
Lastly, the history is really what helps make the diagnosis and testing should be used to help determine the likelihood that the diagnosis is correct. If a patient comes in and requests food allergy testing to a long list of unrelated foods (For example: milk, grains, fruits, seafood, spices), or cannot identify any specific foods as potential causes of their symptoms, then it is very unlikely that they have a true food allergy.
According to your study "Use of Food Allergy Panels by Pediatric Care Providers Compared With Allergists", frequently, what * is * happening next?
Unfortunately, we found that blood testing for a large panel of food allergens is occurring almost half the time when food allergy tests are ordered by primary care clinicians. Instead of testing for individual specific foods suggested by a clinical history, these arbitrary panels are being used a lot of the time.
Why is this a problem?
The problem with ordering a large number of tests for foods is that there are high rates of false positive results. This means that many more patients will have a ‘positive’ test result compared with patients who actually have true allergy.
Blood IgE levels are reported on a scale from 0.1 to 100. Anything above 0.35 is often reported with a big exclamation point beside it, which increases anxiety among both patients and providers. IgE tests are often misinterpreted and poorly understood by the primary care clinicians who order them.
Anyone can order these tests, but they really should only be ordered by clinicians who understand how to interpret the results and apply them to their patients. Allergists receive special training and board certification to perform and interpret IgE tests, but other clinicians can learn to do so as well.
The detection of IgE to a food by testing reveals sensitization. About 30% of all people are sensitized to common food allergens, or will have an elevated level on testing. However, only about 5% of all people are truly allergic to foods. So, if you make a diagnosis by testing alone, then the majority of people will be misdiagnosed as having a food allergy.
IgE tests are far from perfect and should never be considered to be ‘positive’ or ‘negative’. The size of the test result indicates the likelihood that allergy is present. Levels mean different things for different foods, and predictive values have only been established for a few select foods.
The best test to determine if someone is allergic to a food is to eat the food. If immediate onset, reproducible symptoms do not occur, then they are not allergic. The problem with these panel tests is that they include an assortment of foods that patients are usually eating without problems. When the results come back elevated or interpreted as ‘positive’, many patients are then advised to take those foods out of their diet, even when they were eating them for years without problems. Children, especially, can be harmed as parents may be told to avoid giving them foods they haven’t tried yet due to these test results. Aside from being misdiagnosed and having to carry an epinephrine autoinjector when one may not be necessary, people can suffer from nutritional deficiencies when food is restricted from their diet.
Lastly, if a sensitized person (elevated IgE on testing) is eating a food without problems, their immune system is tolerant to that food. If that person removes that food for an extended period of time, their immune system may then become allergic to that same food. Recent studies have shown this can happen in roughly 15% of young children with eczema who have foods removed based upon testing. Now clinicians as a whole are actually creating harm for these patients…and that’s a big problem.
Why this may be happening?
Lack of understanding of food allergies and testing by pcps is multifactorial but likely related to demands on their time and challenges in keeping up with an ever-growing body of evolving scientific evidence and changing clinical guidelines. Limited access to board-certified A/I consultants for patient referrals or A/I training programs for residency elective rotations may contribute as well.
So what are potential next steps for primary care physicians?
Education and dissemination of best practice. The Choosing Wisely series has been in existence for almost 5 years and one of the top evidence-based recommendations is to avoid the use of indiscriminate IgE panels in the evaluation of suspected food allergy. Unfortunately, it can take decades for research and clinical guidelines to permeate and then change practice.
Primary care physicians are fantastic resources for patients given their long-standing relationships with families and ability to care for a wide assortment of conditions. However, given their time constraints, it is nearly impossible for them to remain as up to date as possible on the latest research or guidelines from every specialty.
One way to help educate is through publications in widely read peer reviewed journals. Presentations at local, regional, and national meetings can help as well. Social media and blogs such as yours may also help reach a segment of physicians.
Ultimately, we may need to find a way to limit the availability of food allergy panels by laboratories or provide point of ordering education/alerts to clinicians.
What, if any, are potential next steps for the food allergy community?
Education and dissemination of best practice. I hope that we can all help provide education to others and serve as a reliable resource. Unfortunately, food allergy tests are widely available and in some states, patients can order online without a physician’s order! We all need to work together to help increase awareness and understanding of these tests can and can’t be utilized.
Thank you Dr. Dave!
Dr. Dave is a board certified allergist/immunologist and Associate Professor of Pediatrics at Nationwide Children's Hospital and The Ohio State University College of Medicine. His research interests include dissemination of evidence-based guidelines and best practices as well as use of mobile health applications to improve self management of asthma for children and teenagers. Dr. Dave is active on social media with his Twitter handle @allergykidsdoc and has been invited to train physicians on the use of social media at regional and national conferences. He is also a regular contributor to patient education through published articles on Huffington Post, US News and World Report, and kevinmd.
|Dr Dave Stukus|