In a previous blog entry, What’s Wrong with “I Want My Kid Tested for Food Allergies,” the pitfalls of allergy testing are detailed.
A recent study (DR Stutkus et al.Pediatrics December 2016, VOLUME 138 / ISSUE 6) suggests that primary care providers could used more education on utilizing allergy testing more effectively. The main problem with food allergy testing is its very low positive predictive value. In a previous study of food allergy testing, the positive predictive value of food allergy testing was 2.2%!
Thanks to Kipp Ellsworth for this reference.
BACKGROUND AND OBJECTIVE: Immunoglobullin E (IgE)-mediated food allergies affect 5% to 8% of children. Serum IgE levels assist in diagnosing food allergies but have low positive predictive value. This can lead to misinterpretation, overdiagnosis, and unnecessary dietary elimination. Use of IgE food allergen panels has been associated with increased cost and burden. The scale of use of these panels has not been reported in the medical literature.
METHODS: We conducted a retrospective review of a commercial laboratory database associated with a tertiary care pediatric academic medical center for food IgE tests ordered by all provider types during 2013.
RESULTS: A total of 10 794 single-food IgE tests and 3065 allergen panels were ordered. Allergists ordered the majority of single-food IgE tests (58.2%) whereas 78.8% of food allergen panels were ordered by primary care providers (PCPs) (P < .001). Of all IgE tests ordered by PCPs, 45.1% were panels compared with 1.2% of orders placed by allergists (P < .001). PCPs in practice for >15 years ordered a higher number of food allergen panels (P < .05) compared with PCPs with less experience. Compared with allergists, PCPs ordered more tests for unlikely causes of food allergies (P < .001). Total cost of IgE testing and cost per patient were higher for PCPs compared with allergists.
CONCLUSIONS: Review of food allergen IgE testing through a high volume outpatient laboratory revealed PCPs order significantly more food allergen panels, tests for uncommon causes of food allergy, and generate higher cost per patient compared with allergists. These results suggest a need for increased education of PCPs regarding proper use of food IgE tests.