Efficacy of very-low-dose oral food challenge in children with severe hen egg allergy: A retrospective, single-center case series.

BACKGROUND: To avoid complete elimination of hen eggs (HE) from diet, we introduced a very-low-dose (VLD) oral food challenge (OFC) in patients with severe HE allergy in 2019. Herein, we investigated the efficacy of VLD HE OFC for achieving the full dose OFC.

METHODS: Patients with an overt allergic reaction to LD (1/32 HE [≤100 mg]) or less, egg white (EW) protein within 6 months were included. In the VLD group, patients not achieving full-dose OFC (1/2 HE: 1600 mg EW protein) within 2 years were excluded. We retrospectively compared the rate of passing a full-dose OFC between patients who underwent a LD OFC before 2019 (LD group) and those who underwent a VLD OFC (1/100 HE: 32 mg EW protein) after 2019 (VLD group). The period for passing the full-dose OFC was evaluated using Kaplan-Meier survival analysis.

RESULTS: We enrolled 411 and 111 patients in the LD and VLD groups, respectively. The median age at OFC initiation was 2.2 [1.5-3.6] and 2.1 [1.4-3.2] years in the LD and VLD groups, respectively. EW- and ovomucoid-specific IgE levels were 38.3 (12.5-72.9) and 21.0 (8.3-46.2) kUA /L in the LD group and 49.8 [18.8-83.9] and 32.1 [15.6-67.8] kUA /L in the VLD group, respectively. Over 4 years, the LD and VLD groups passed the full-dose OFC at rates of 70 and 95%, respectively, with significant differences (log-rank test, P < 0.001).

CONCLUSIONS: VLD HE OFC may contribute to passing a full-dose OFC in patients with severe HE allergies.