Placebo effects in allergen immunotherapy-An EAACI Task Force Position Paper.

Area of Science:

• Allergy and Immunology
• Clinical Trial Methodology
• Neuroscience

Background:

• The placebo effect, driven by patient expectations, involves complex neuro-immune interactions.
• Ethical concerns arise when placebo groups are denied effective treatments, particularly in long-term studies.
• Placebo effects are notably large in allergen immunotherapy (AIT) clinical trials, impacting results.

Purpose of the Study:

• To comprehensively analyze the placebo effect in AIT clinical trials.
• To address challenges related to comorbidities, blinding, adherence, and outcome measurement in AIT.
• To propose solutions for optimizing future AIT trial design.

Main Methods:

• Review of existing literature and data on placebo effects in AIT.
• Analysis of regulatory requirements for double-blind, placebo-controlled (DBPC) trials.
• Expert consensus and position paper development by the European Academy of Allergy and Clinical Immunology (EAACI) Task Force.

Main Results:

• Placebo effects in AIT trials can be substantial, reaching up to 77% relative to pretreatment scores.
• Key factors influencing the placebo effect include psychological and physiological patient expectations.
• Significant methodological limitations exist in current AIT trial designs regarding placebo assessment.

Conclusions:

• The placebo effect in AIT requires careful consideration due to its magnitude and potential to confound results.
• Future AIT trials need enhanced designs addressing neuroimmunological mechanisms, ethical issues, and methodological limitations.
• Standardized approaches are needed to accurately measure and manage placebo effects in AIT research.