Food Allergy Overdiagnosed With IgE Tests
Frontline Medical News, 2014 May 13, S Boschert
PracticeUpdate.com

SAN DIEGO (FRONTLINE MEDICAL NEWS) – Unwarranted food allergy testing in 67% of 274 patients who underwent testing identified a new food allergen in only 4 patients, in a retrospective study.

The review of charts on patients referred to a tertiary food allergy center from September 2011 to December 2012 found 274 children with results from a standard panel of food-specific IgE tests obtained prior to referral. Only 33% of cases warranted evaluation for food allergy according to criteria set by the National Institute of Allergy and Infectious Diseases, according to Dr. Maryam Saifi and her associates.

In the 90 patients who underwent food allergy testing appropriately, testing identified a previously unknown allergen in 38 patients (42%) and found no new allergen in 52 (58%). When food allergy testing was not warranted, however, testing identified a previously unknown allergen in only 4 of 184 patients (5%) and no new allergen in 180 patients (95%), Dr. Saifi reported in a poster presentation at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.

The most common reason for conducting food-specific IgE panel testing in patients who did not meet criteria for testing was allergic rhinitis, followed by mild atopic dermatitis, urticaria, GI complaints, rash (not otherwise specified), angioedema without urticaria, and cough.

Test results and recommendations from primary care providers led 126 of the 274 patients to alter their diets (46%), yet only 54 food-avoiding patients had a history warranting evaluation for food allergy (20% of the whole cohort), reported Dr. Saifi, a pediatrician at the University of Texas Southwestern Medical Center, Dallas.

Diet-altering patients were avoiding foods such as milk, eggs, peanuts, tree nuts, soy, wheat, fish, shellfish, sesame seed, corn, chocolate, or beef. After being seen at the referral clinic for a history, repeat testing, and observed challenges when necessary, patients were able to reintroduce an average of two foods per person, most commonly among milk, eggs, peanuts, soy, and wheat. All patients who had been avoiding corn and chocolate were able to reintroduce those foods.

Serum allergy testing should be used judiciously and only when indicated by history and physical exam, Dr. Saifi concluded. IgE panels for food allergy seem to have little utility as screening tests and often lead to misdiagnosis of food allergy, resulting in inappropriate food avoidance that could cause nutritional deficiencies, increased anxiety, and lower quality of life, she said.

The study excluded patients diagnosed with eosinophilic esophagitis and patients whose records lacked results from food-specific IgE tests prior to referral.

The investigators’ financial disclosures were not available.

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