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# Guidance on Non-inferiority Drug Effectiveness Studies
- URL: https://www.fdaweb.com/guidance-on-non-inferiority-drug-effectiveness-studies/
- Published: 2016-11-07T12:00:00.000Z
- Updated: 2026-09-14T21:45:43.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5137269

FDA has posted a [guidance](http://www.fda.gov/downloads/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/UCM202140.pdf?ref=fdaweb.com) on “Non-Inferiority Clinical Trials to Establish Effectiveness” that discusses the appropriate use of such study designs to provide evidence on the effectiveness of a drug or biologic. The document says that a non-inferiority design is usually used because a superiority study design (drug versus placebo, dose response, or superiority to an active drug) cannot be used. it gives advice on when non-inferiority (NI) studies intended to demonstrate effectiveness of an investigational drug can provide interpretable results, how to choose the NI margin, and how to test the NI hypothesis. It does not provide recommendations for the use of NI study designs to evaluate a drug’s safety.

This guidance consists of four parts. The first is a general discussion on regulatory, study design, scientific, and statistical issues associated with the use of NI studies. The second part focuses on more detailed statistical approaches used to determine the NI margin and to test for non-inferiority. The third addresses commonly asked questions about such studies. And the fourth part includes four examples of successful and unsuccessful efforts to define NI margins and test for non-inferiority.