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

In RCTs, when the aim is to show that two treatments are not significantly different, what type of study is being conducted?

1. Non-inferiority Study

2. Superiority Study

3. Equivalence Study

4. Factorial Study

The correct answer is: Equivalence Study

In randomized controlled trials (RCTs), when the goal is to demonstrate that two treatments are not significantly different from each other, the study being conducted is classified as an equivalence study. This type of study aims to establish that the effects of two interventions are so similar that they can be considered interchangeable in terms of their efficacy or safety. Equivalence studies often set predefined margins to determine what is considered 'not significantly different'. If the results fall within these margins, one can conclude that the two treatments have roughly the same effects, thereby supporting the claim of their equivalence. This methodology is particularly useful when clinicians want to show that a new treatment is just as effective as an established treatment, yet may offer other benefits, such as fewer side effects or lower costs. In contrast, non-inferiority studies aim to show that a new treatment is not worse than an existing treatment by more than a specified margin, while superiority studies seek to demonstrate that one treatment is better than another. Factorial studies, on the other hand, investigate more than one intervention simultaneously, allowing researchers to assess the effects of multiple treatments across different combinations. Understanding these distinctions helps in the proper interpretation of trial results and their implications in clinical settings.