Association of Clinical Research Professionals (ACRP) Certified Professional Practice Exam

Which type of study is designed to determine if a new treatment is at least as effective as the standard treatment?

1. Superiority Study

2. Non-inferiority Study

3. Equivalence Study

4. Factorial Study

The correct answer is: Non-inferiority Study

A non-inferiority study is specifically designed to evaluate whether a new treatment is at least as effective as a standard treatment, rather than proving it superior. This type of study sets a threshold (or margin) to demonstrate that the new treatment does not perform significantly worse than the established treatment, allowing researchers to conclude that the new treatment is a viable alternative. In non-inferiority studies, the key focus is on establishing that the proposed treatment is "not worse" than the standard treatment by more than a predetermined amount. This is particularly useful in clinical scenarios where a new treatment could offer other benefits, such as fewer side effects or easier administration. In contrast, a superiority study aims to prove that one treatment is better than another, while an equivalence study focuses on demonstrating that two treatments are similar in effectiveness, often within a predefined margin of equivalence. A factorial study is designed to explore multiple interventions simultaneously and their interaction effects but does not specifically aim to compare with a standard treatment in the same context.