A comparison of double-blind, placebo-controlled food challenge and open food challenge

Double-blind, placebo-controlled food challenge (DBPCFC) remains the gold standard for diagnosing food allergy, despite sparse comparisons to open food challenges (OpenFCs). The objective of this retrospective study was to compare severity of symptoms and threshold values (cumulative dose of food allergen eliciting a clinical reaction) in children and adults with peanut allergy, challenged in an open and/or double-blind, placebo-controlled protocol.

This study included patients from the Allergy Centre, Odense University Hospital with a positive oral food challenge, defined as strict objective signs, with peanut during the period 2001-2022. Severity of symptoms was graded using the Sampson's severity score. Distribution models of threshold values were calculated using log-normal interval-censored survival analysis, and the number of placebo reactions was evaluated.

In total, 318 positive OpenFCs and 86 DBPCFCs were included. There was no difference in severity of symptoms nor threshold values comparing the two challenge types, neither when stratified for age groups. However, a higher proportion of children experienced Grade 3 symptoms in the double-blind group. Only one patient had a positive reaction to a placebo challenge.

Our findings do not advocate for DBPCFC being superior to OpenFC, if the latter is performed with strict objective stop criteria by trained staff.