Clinical Trial

Key facts

NIH definition

People prospectively assigned to interventions to measure health outcomes

FDA rules for drug trials

21 CFR Parts 50 (consent), 56 (IRBs) and 312 (IND)

Registration law

FDAAA Section 801, implemented by 42 CFR Part 11

Public U.S. registry

ClinicalTrials.gov, run by the National Library of Medicine

Study types on ClinicalTrials.gov

Interventional, observational and expanded access

What is a clinical trial?

The National Institutes of Health (NIH) defines a clinical trial as a research study in which one or more human subjects are prospectively assigned to one or more interventions, which may include a placebo or other control, to evaluate the effects of those interventions on health-related biomedical or behavioral outcomes. The key word is assigned: the protocol decides who receives what, rather than researchers observing care that happens anyway.

Clinical trials test drugs, biologics, medical devices, surgical procedures, diagnostics, diets and behavioral programs. Drug and biologic trials in the United States usually run under an Investigational New Drug Application (IND) filed with the Food and Drug Administration (FDA), while significant-risk device studies run under an Investigational Device Exemption (IDE).

An observational study, in which researchers follow people receiving their usual care without assigning an intervention, is not a clinical trial under this definition, even though ClinicalTrials.gov registers observational studies too.

How a clinical trial is run

Drug development trials are grouped into Phases 1 through 4, which differ in purpose and size, but most interventional trials follow the same basic sequence:

• A sponsor writes a protocol that states the question, the eligibility criteria, the interventions, the endpoints and the statistical plan.
• An Institutional Review Board (IRB) reviews and approves the protocol and consent documents before any participant enrolls.
• Sites recruit participants, obtain informed consent and deliver the intervention under a principal investigator.
• Data are collected, monitored and analyzed against the prespecified primary endpoint.
• Results go to regulators, to ClinicalTrials.gov when required, and often to peer-reviewed journals.

Why clinical trials matter

Trials are how new products earn FDA approval and how existing products gain new indications, so trial activity is one of the earliest public signals of where a therapeutic market is heading.

• Competitive intelligence teams track trials by condition, phase and sponsor to map rival pipelines years before launch.
• Site selection and feasibility teams use trial location histories to find investigators and institutions with experience in a disease area.
• Investors and analysts watch primary completion dates because results often move company valuations.
• Market access teams read trial designs and comparators to anticipate the evidence a product will bring to payer coverage decisions.