A clinical trial is any research study that prospectively assigns human participants* or groups of humans to one or more health-related interventions** to evaluate the effects on health outcomes. (

* healthy as well as diseased people

** psychological, physical, medical and nutritive treatments as well as surgical and diagnostic procedures, nursing care measures, etc.


The aim of clinical trials is to test the efficacy and safety of drugs or treatments as well as of medical interventions and devices.
Clinical trials help answer scientific questions and improve medical treatments.

A clinical trial is organized, conducted, monitored and evaluated by pharmaceutical, cosmetic and medical device companies and/or a contract research organization in cooperation with clinicians, ethics committees and authorities.
Clinical trials are based on gaining knowledge and must be strictly separated from marketing activities.

Procedure of a prospective*** trial: 

  • Planning (design, protocol, trial folder)
  • Survey (intervention, monitoring, audit****)
  • Completion (data management, evaluation, interpretation, final report, publication)

*** A prospective trial is the review of the medical or psychological efficacy of a treatment.

**** Audit: A systematic and independent review of trial-related activities and documents to determine whether the reviewed trial-related activities were conducted in accordance with the protocol, the sponsor’s standard operating procedures (SOPs), the good clinical practice (GCP), and the valid legal regulations, and whether the data was documented, evaluated and correctly reported according to these requirements.

Types of clinical trials

Commercial clinical trials

These are clinical trials ordered by, for example, pharmaceutical or medical device companies. The sponsor takes the initiative and also assumes many responsibilities since the clinical trials are conducted for commercial purposes (e.g. approval of drugs or CE marking of a medical device).

Noncommercial clinical trials

These are academic or investigator-driven clinical trials. Single doctors or academic study groups and institutions, respectively, take the initiative and assume responsibility.

Different approaches exist for both commercial and noncommercial clinical trials:

Interventional vs. observational trials (intervention in the course of the trial vs. no intervention)
Monocenter vs. multicenter trials  (one clinical center vs. several clinical centers)
Controlled vs. uncontrolled trials  (comparison between placebo, standard and zero therapy vs. no comparison)
Randomized vs. non-randomized trials  (assignment by chance vs. assignment based on a system)
Blind vs. double-blind vs. open-label trials  (unawareness of participants vs. unawareness of both participants and researchers vs. awareness of both)
Crossover vs. parallel trials  (both test groups receive both treatments in alternating order vs. each test group always has the same order)
Confirmatory vs. exploratory trials  (argumentation for a hypothesis vs. collecting background information for later argumentation)
Prevalence vs. equivalence trials  (demonstration that the drug is better vs. demonstration that the drug is not worse)