Why is the NIH definition of a clinical trial so broad?

We are dealing with a serious problem. NIH-funded scientists are not publicizing nearly half of the trials they conduct and complete in a timely manner. This is an unacceptable state of affairs. Our purpose in defining clinical trials as we do is to improve dissemination and transparency. The bottom line: if public money is going to be spent to conduct experiments on people, you are expected to report the results. It is not right to conduct experiments on people (at taxpayer expense) and keep the results secret.

What is the difference between clinical research and a clinical trial?

Clinical trials are clinical research studies.

Clinical research includes all research involving human participants. It does not include secondary studies using existing biological specimens or data collected without identifiers or data that are publicly available. (https://humansubjects.nih.gov/glossary)

Clinical trials are clinical research studies involving human participants assigned to an intervention in which the study is designed to evaluate the effect(s) of the intervention on the participant and the effect being evaluated is a health-related biomedical or behavioral outcome.

Does the primary outcome of a study need to be a health-related outcome in order for a study to be considered a clinical trial?

If any outcome is health-related and the answers to the four questions are all yes, then the study meets the clinical trial definition. You should note, though, that all NIH-funded research investigating biomedical or behavioral outcomes is considered to be health-related. Hence, if the outcome is biomedical or behavioral, the study may be a clinical trial (if the answers to the other three questions are “yes”). Many clinical trials are “mechanistic” or “exploratory” falling outside the realm of efficacy or effectiveness trials.