Clinical research & EBM · Reference
What is a clinical trial?
A clinical trial is a prospective research study that evaluates a health intervention in human volunteers under a pre-specified protocol. It is the principal method for testing whether a treatment, device or procedure is effective and safe.
How a clinical trial is structured
Every clinical trial runs to a written protocol that fixes its objectives, eligibility criteria, intervention, comparator, outcome measures and statistical analysis plan before any participant is enrolled. Participants give informed consent and are usually allocated to a treatment group and a comparison group, often a placebo or standard-of-care arm. The most rigorous designs use random allocation and blinding to limit bias. Outcomes are then compared between groups using the pre-specified analysis, so that any observed difference can be attributed to the intervention rather than to chance or systematic error.
Phases and progression
Drug trials are conventionally organised into phases, from small early-stage studies that assess safety in a few volunteers through to large comparative studies and post-marketing surveillance. Each phase answers a narrower question and gates progression to the next, so that larger and longer studies are only undertaken once earlier evidence is encouraging. This staged design is a methodological safeguard: it concentrates risk in small, closely monitored studies and reserves population-scale evaluation for interventions that have already cleared earlier hurdles.
Governance and reporting
Clinical trials are conducted under Good Clinical Practice (the ICH-GCP standard) and are reviewed by an independent ethics committee or institutional review board before they begin. In most jurisdictions interventional trials must be registered on a public register such as ClinicalTrials.gov before enrolment, which guards against selective reporting.
When results are published, the randomized controlled trial reporting standard CONSORT specifies what authors must disclose, from the flow of participants to the pre-registered outcomes. Registration plus structured reporting together make a trial auditable and reproducible.
Key facts
At a glance
- Definition: Prospective study of an intervention in people
- Governed by: ICH-GCP; ethics committee / IRB approval
- Design tools: Randomisation, control group, blinding
- Registered: ClinicalTrials.gov and other public registers
- Reported via: CONSORT statement (for randomized trials)
- Staged as: Phase 0 through Phase 4
Common questions
FAQ
What is the purpose of a clinical trial?+
A clinical trial is designed to test specific questions about a health intervention, such as whether it works, how it compares with an alternative, and what side effects it produces. It generates the controlled evidence that regulators and clinicians rely on. It is a research method, not a route to personal medical advice.
How is a clinical trial different from an observational study?+
In a clinical trial the researchers assign the intervention, often at random, whereas in an observational study they only watch what happens without intervening. Assignment by the investigator is what lets a well-conducted trial support stronger causal conclusions.
Who oversees clinical trials?+
Trials are overseen by an independent ethics committee or institutional review board and are conducted under Good Clinical Practice. Interventional trials are also registered on public registers, and many are monitored by an independent data safety monitoring board.
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