Describes the nature of a clinical study. Types include:
- Observational study — observes people and measures outcomes without affecting results.
- Interventional study (clinical trial) — studies new tests, treatments, drugs, surgical procedures or devices.
- Medical records research — uses historical information collected from medical records of large groups of people to study how diseases progress and which treatments and surgeries work best.
During the early phases (phases 1 and 2), researchers assess safety, side effects, optimal dosages and risks/benefits. In the later phase (phase 3), researchers study whether the treatment works better than the current standard therapy. They also compare the safety of the new treatment with that of current treatments. Phase 3 trials include large numbers of people to make sure that the result is valid. There are also less common very early (phase 0) and later (phase 4) phases. Phase 0 trials are small trials that help researchers decide if a new agent should be tested in a phase 1 trial. Phase 4 trials look at long-term safety and effectiveness, after a new treatment has been approved and is on the market.