KCE Glossary

A clinical trial is a scientific study in humans to evaluate the safety and effectiveness of a treatment or diagnostic or preventive method. A clinical trial investigates whether a medical intervention works, is safe, and is better than existing care. The participants are volunteers, often with a specific condition. They always give their informed consent.

Types of clinical studies:

1.    Randomised controlled trial (RCT)
→ The “gold standard”: participants are randomly divided into groups (randomisation). One group receives the new treatment and the other group receives a placebo or standard care. The 2 groups are compared to see how effective the experimental treatment was. Not all controlled clinical trials are randomized. If patients are randomly allocated to treatment and comparison groups, this is called a randomised controlled trial. The study is often blinded.

2.    Interventional study
→ participants receive a new treatment (e.g. a medicine), but not always through randomisation. The researchers monitor its effect.

3.    Observational study
→ participants receive their usual care, and the researchers observe what happens and collect data on symptoms, treatments, outcomes, etc. Also see Cohort study.

Phases of a clinical trial:
•    Phase 1: safety testing on a small group of healthy volunteers
•    Phase 2: testing of efficacy and side effects in a small group of patients
•    Phase 3: larger study to confirm efficacy and safety
•    Phase 4: after approval, monitoring of long-term effects and use in practice

KCE Trials is a programme for the funding of non-commercial clinical trials, financed by the Belgian federal government.

More information can be found here.