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How a volunteer is selected for a clinical study

Selection begins with a talk and informed consent. Then the doctor carries out an examination and checks whether you meet the protocol criteria. The decision is made by the study doctor on the basis of those criteria.

Published: 21 October 2026 Updated: 21 October 2026 4 min read

First step: a call or a request

You call the clinic or leave a request on the website. The administrator tells you which studies are currently recruiting and books you in for a talk. At this stage no medical information is collected through the website: diagnoses and medical history are discussed by the doctor in person.

The study doctor explains the aim of the study, the procedures, the risks and the benefits, and answers your questions. If you agree to take part, you sign the informed consent form. More in the article “Informed consent”.

Examination

After you sign the consent, the doctor carries out a medical examination. It usually includes a talk about your health and the medicines you take, a physical examination, measurement of vital signs, an electrocardiogram (ECG) and laboratory tests. The exact list depends on the study protocol.

Checking the criteria

The doctor compares the examination results with the inclusion and exclusion criteria in the protocol. They are the same for all candidates and protect you above all: a study is conducted only with people for whom it is safe.

What happens next

If you are suitable, you are told the schedule of visits or hospital stay and the rules of participation (for example, meals and restrictions on medicines and alcohol) — the doctor explains them. If you are not suitable, you will be told the reason, within what can be disclosed, and told about other studies if there are any.

Questions and answers are in the “Volunteers” section.

Questions and answers

Why might I not be enrolled in a study if I am healthy?

Every study has its own inclusion and exclusion criteria: age, examination results, concomitant medicines and other parameters. Being turned away does not mean there is anything wrong with your health: the protocol simply requires a particular set of conditions.

Do I need to prepare for the examination?

The administrator will tell you which documents to bring and how to prepare when you book. Come to the examination at the agreed time.

See also

Thinking of becoming a volunteer?

Call us or send a request: our coordinator will tell you which studies are currently enrolling.