Placebo reactions in double-blind, placebo-controlled food challenges in children
Article first published online: 6 JUL 2007
Volume 62, Issue 8, pages 905–912, August 2007
How to Cite
Vlieg-Boerstra, B. J., Van Der Heide, S., Bijleveld, C. M. A., Kukler, J., Duiverman, E. J. and Dubois, A. E. J. (2007), Placebo reactions in double-blind, placebo-controlled food challenges in children. Allergy, 62: 905–912. doi: 10.1111/j.1398-9995.2007.01430.x
- Issue published online: 6 JUL 2007
- Article first published online: 6 JUL 2007
- Accepted for publication 16 April 2007
- double-blind, placebo-controlled food challenge;
- food allergy;
- food challenge;
- placebo event
Background: A cardinal feature of the double-blind, placebo-controlled food challenge (DBPCFC) is that placebo administration is included as a control. To date, the occurrence and diagnostic significance of placebo events have not extensively been documented.
Objective: To analyse the occurrence and features of placebo events in DBPCFCs and to assess their contribution to the diagnostic accuracy of the DBPCFC in children.
Methods: The study population consisted of 132 challenges in 105 sensitized children (age range 0.7–16.6 years, median 5.3 years), who underwent DBPCFCs with cow’s milk, egg, peanut, hazelnut and soy. Placebo and active food challenges were performed on different days.
Results: A total number of 17 (12.9%) positive placebo events occurred, which could be classified as immediate (9/17), late-onset (8/17), objective (11/17) or subjective (6/17). Four of 74 (5.4%) positive active food challenges were revealed to be false positive by administration of a placebo challenge. This is 3% (4/132) of all challenges. When computed by a statistical model, the false positive rate was 0.129 (12.9% of all challenges).
Conclusion: Placebo events with diverse clinical characteristics occur in DBPCFCs in a significant number of children. The diagnostic significance of the administration of a placebo challenge is first, to identify false positive diagnoses in DBPCFCs by refuting false positive tests in individual patients. Secondly, to allow for blinding of the active food challenge. Thirdly, applying a statistical model demonstrates that some positive challenges may be false positive and that the test may need to be repeated in selected cases.