Differences in egg and milk food challenge outcomes based on tolerance to the baked form.

Background: Previous studies suggest inclusion of baked egg and milk in the diet of children with egg or cow's milk (CM) allergy might positively affect native tolerance. However, differences in native food reactivity based on historical baked tolerance are not fully understood.

Objective: To assess differences in native egg and CM oral food challenge (OFC) outcomes based on presenting history of tolerance and exposure to these foods in the baked form.

Methods: This study is a retrospective review of all egg and CM OFCs at the Children's Hospital of Philadelphia (Philadelphia, Pennsylvania) over 4 years (N = 580). History of baked ingestion was compared with OFC pass rate, eliciting dose, epinephrine use, reaction classification, and recent skin test reaction or specific immunoglobulin E level.

Results: There were 115 egg- and 70 CM-positive challenge reactions, with most eliciting anaphylaxis. Children tolerating baked egg passed OFC more frequently (75%) compared with children who avoided baked egg (58%; P = .01) or never ingested egg (45%; P < .0001). For positive reactions, children tolerant of baked egg reacted at higher eliciting doses of native egg (median 3.0 g, range 0.125-15.75 g) compared with those avoiding baked egg (median 0.69 g, range 0.13-10.0 g; P = .03) and those with no egg exposure (median 0.88 g, range 0.13-13.88 g; P = .01). Further, epinephrine use was lower in children tolerating baked egg (10%) compared with children avoiding baked egg (22%; P = .02) and compared with children who never ingested egg (32%; P = .0001). These differences were not observed for CM challenges.

Conclusion: Children who historically tolerated baked egg were less sensitive to native egg during OFC compared with children whose baked reactivity was largely unknown.