## What is a non-inferiority trial?

A study that tests whether a new treatment is not worse than an active treatment it is being compared to. Non-inferiority trials are sometimes done when a placebo (an inactive treatment) cannot be used.

## What is the difference between non-inferiority and equivalence trials?

Non-inferiority trials aim to show that the new drug is no worse than standard treatment. Equivalence trials aim to show the new treatment is no better and no worse. This is the definition of what would be the minimum important difference between the treatments.

**Can a non-inferiority trial show superiority?**

To conclude, non-inferiority trials do have tremendous utility in modern medicine as more and more drugs or treatments are being developed ever so often and these need to be rigorously tested against established guideline based practices.

### What is the difference between a non-inferiority trial and a superiority trial?

A superiority trial is designed to show that a new treatment is better than an active control or placebo. A non-inferiority trial is different as it is designed not to show that treatments are equal, or ‘not different’, but that the new treatment is not unacceptably worse than, or ‘non-inferior’ to, an active control.

### Why use a non-inferiority trial?

Why noninferiority trials? Noninferiority trials may be performed to demonstrate that a new treatment is better than an assumed placebo in situations where conducting a placebo control trial is unethical.

**What do equivalence trials aim to prove?**

In an equivalence trial, the statistical test aims at showing that two treatments are not too different in characteristics, where “not too different” is defined in a clinical manner. Finally, in a non-inferiority trial, the aim is to show that an experimental treatment is not (much) worse than a standard treatment.

## How do you test for non-inferiority?

In noninferiority testing, a common practice is to set the value of δ to a fraction, f, of the lower limit of a confidence interval of the difference between the current therapy and the placebo obtained from a meta-analysis.

## What is an acceptable noninferiority margin?

In order to demonstrate non-inferiority, the recommended approach is to pre-specify a margin of non- inferiority in the protocol. After study completion, a two-sided 95% confidence interval (or one-sided 97.5% interval) for the true difference between the two agents will be constructed.