Dropouts in sublingual allergen immunotherapy trials - a systematic review

Area of Science:

• Allergy and Immunology
• Clinical Trials Methodology
• Respiratory Medicine

Background:

• Participant dropouts can compromise the statistical power of clinical trials.
• Understanding dropout rates and reasons is crucial for both study design and real-world adherence to immunotherapy.
• Sublingual immunotherapy (SLIT) is a common treatment for respiratory allergies.

Purpose of the Study:

• To systematically review dropout rates in published double-blind, placebo-controlled randomized clinical trials of SLIT for respiratory allergic diseases.
• To analyze dropout rates based on various factors including allergen type, formulation, and patient demographics.
• To compare dropout rates between active SLIT and placebo groups.

Main Methods:

• Systematic review of published double-blind, placebo-controlled randomized clinical trials.
• Inclusion of studies on SLIT for respiratory allergic diseases.
• Analysis of dropout data from 81 studies involving 9998 patients.

Main Results:

• The overall composite dropout percentage in SLIT controlled studies was 14% (95% CI: 11.9-16), indicating it is not a major problem.
• Dropout rates were comparable between participants receiving active SLIT and those receiving placebo.
• No significant differences in dropout rates were observed across different allergens, formulations, or patient characteristics.

Conclusions:

• Dropout rates in controlled SLIT studies for respiratory allergies are generally low and do not differ between active and placebo treatments.
• The low dropout rate supports the reliability of positive clinical outcomes reported in meta-analyses of SLIT trials.
• Findings suggest good adherence and tolerability for SLIT in clinical trial settings.