A literature review from the Stanford University School of Medicine’s Center for Primary Care and Outcomes Research has uncovered several sources of confusion that could lead to misdiagnosis or mismanagement of food allergy.
“The evidence for the prevalence and management of food allergy is greatly limited by a lack of uniformity for criteria for making a diagnosis,” the authors conclude (JAMA. 2010;303:1848-1856).
The systematic review of 72 studies found the evidence on the prevalence, diagnosis, management, and prevention of food allergies to be “voluminous, diffuse, and critically limited by the lack of uniformity for the diagnosis of a food allergy, severely limiting conclusions about best practices for management and prevention.”
Food challenges, skin-prick testing, and serum food-specific immunoglobulin (Ig)E studies all have a place in food allergy diagnosis, observed the investigators, but none of these methods is specific enough, sensitive enough, or easy enough to use to warrant recommendation over others.
Patients with such nonspecific symptoms as rash or abdominal complaints and positive skin-prick tests or serum food-specific IgE studies are less than 50% likely to have a food allergy. “Inappropriately diagnosing such individuals with food allergy may unnecessarily subject them to broad dietary restrictions, the risk of nutritional problems from elimination diets (e.g., milk or egg elimination in children), significant anxiety and worry, and the social challenges food allergies cause,” cautioned the authors.
The researchers assert that to properly interpret skin-prick tests and serum food-specific IgE results and weed out the false-positive findings, practitioners must evaluate the data within the context of the patient’s clinical history and understand the symptoms of clinical food allergy. The group also calls for a uniform set of criteria to denote what constitutes a food allergy and evidence-based guidelines on which to make the diagnosis.
The review yielded these additional key findings:
- Food allergies affect more than 1%-2% but less than 10% of the population; whether the prevalence is increasing is unclear.
- Elimination diets are the mainstay of treatment, but the investigators found only one randomized controlled trial examining this therapy.
- Immunotherapy, which is not approved for the treatment of food allergy, may help with desensitization, but whether it can lead to long-term tolerance of a food is not yet known.