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Updated: Jan 16, 2026
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Published on: September 20, 2019
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Ethical clinical trial design and differences in treatment effects
Roger J Lewis1, Kert Viele1, Margareth Ndomondo-Sigonda2
1Berry Consultants, LLC, 3345 Bee Caves Rd, Suite 201, Austin, Texas78746, United States of America.
Bulletin of the World Health Organization
|October 2, 2025
Summary
Global clinical trials can mislead if they assume one treatment effect fits all. Hierarchical modeling offers a solution, providing region-specific results and upholding justice in research for all populations.
Area of Science:
- Clinical Trials
- Biostatistics
- Health Equity
Background:
- Global clinical trials often estimate a single overall treatment effect.
- This approach can lead to misleading conclusions and ethical concerns, particularly regarding justice.
- Justice is compromised when research in low-resource settings primarily benefits high-resource settings.
Purpose of the Study:
- To propose a methodological strategy for global clinical trials to address ethical concerns related to justice.
- To enable the estimation of valid, population-specific treatment effects.
- To maintain analytical efficiency comparable to traditional pooled analyses.
Main Methods:
- Utilized a methodological strategy based on hierarchical modeling.
- Applied hierarchical modeling to estimate treatment effects for each participating population.
- Demonstrated the approach with a specific example.
Main Results:
- Hierarchical modeling enables the estimation of treatment effects valid for each participating population.
- The approach can retain efficiency comparable to traditional pooled analysis.
- Produces valid, region-specific results when substantial between-population differences exist.
Conclusions:
- Hierarchical modeling offers a strategy to ensure global clinical trials are designed ethically.
- This method helps preserve justice for all participant populations.
- Adoption into trial standards would support regulators, funders, and stakeholders in ensuring equitable research.
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