All terms
Clinical & TrialsClinical Evidence
Non-Inferiority Trial
A trial designed to demonstrate that a new intervention is not worse than an active comparator by more than a pre-specified, clinically acceptable margin.
Reviewed by Christian Espinosa, Founder, Blue Goat CyberLast reviewed May 9, 2026
Definition
A non-inferiority trial is designed to demonstrate that a new intervention is not unacceptably worse than an active comparator. The pre-specified non-inferiority margin (delta) defines the largest difference that would still be considered clinically acceptable; a one-sided 95% confidence interval that excludes a difference worse than the margin establishes non-inferiority. Common in MedTech when a placebo or sham control would be unethical (e.g., comparing a new drug-eluting stent against an established one). What the regulation says
FDA Guidance: 'Non-Inferiority Clinical Trials to Establish Effectiveness' (November 2016). EMA: CHMP Points to Consider on Non-Inferiority. ICH E10 'Choice of Control Group' provides the foundational framework.
What this means in practice
Margin selection is the most contested element. FDA expects the margin to be both clinically defensible and to preserve a meaningful fraction of the comparator's effect over placebo (the 'M1/M2' framework). Common pitfalls
- •Choosing a margin that's clinically defensible but doesn't preserve enough of the active comparator's effect — FDA will reject the design.
- •Running a non-inferiority trial with poor protocol adherence — drift biases toward the null and toward false NI conclusions.
Primary references
3 sourcesLink health: 2 verified 1 bot-blocked· last checked 2026-05-09
FDA·1ICH·2
- 1
FDA Guidance — Non-Inferiority Clinical Trials (2016)Bot-blockedFDAfda.gov
- 2
ICH E10 Choice of Control GroupVerifiedICHich.org
- 3
ICH GuidelinesVerifiedICHich.org
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