Clinical Research
Reliable Evidence from Small Populations: Rare-Disease Design Options
Evaluate precision, Bayesian methods, repeated measures, adaptive designs and external controls when populations are limited.
Admin
June 20, 2026
8 min read
Rare populations do not remove the need for rigorous inference
When patients are scarce, the goal is to maximise reliable information rather than mechanically target 80% power.
Practical framework
Strengthen natural-history evidence.
Consider repeated-measure or crossover efficiency.
Use transparent Bayesian priors.
Assess bias in external controls.
Reporting
Report feasibility limits, precision, assumptions and design alternatives.
Common mistakes
Using rarity to justify weak reporting.
Treating historical controls as randomised.
Using informative priors without sensitivity analysis.
References
Accessed 20 June 2026. General methodological information.