Clinical trial is a study that investigates the safety and efficacy of an investigational medicinal product. Usually, the investigational product and its treatment outcomes are compared to another product or placebo. This is done by dividing the trial participants into groups (arms) according to a predefined protocol. Clinical trials always require a regulatory authority approval and ethics committee review. When you volunteer to take part in a clinical trial, you help doctors and researchers learn more about medicines and their ability to treat and prevent diseases.

Participating in clinical trials is voluntary. Before a trial begins, the trial staff explains you the details of the trial. This helps you decide whether to participate. These details are included in a document called an informed consent form. “Informed” here means that you have been informed about all the key aspects of the trial and you have read and understood the materials given to you. If you decide to participate, you must then give your consent by voluntarily signing the document before entering the trial.

An investigational medicinal product or study medication is an active ingredient or placebo that has been prepared for human use and is being tested or compared in a clinical trial. This is the product you will be given as part of your participation in the trial.

In clinical trials, a placebo is a product that does not contain any active ingredients and thus, has no medical effects. The placebo effect is a positive or negative effect that a patient perceives after taking the placebo although they have not been given any medicine.

In clinical trials, indication refers to a health condition or disease for which a medicinal product is meant to be used. If we use a simple example, a commonly used painkiller ibuprofen is indicated among other for headache, i.e. it is used to alleviate the symptoms of headache.

When a person registers for a clinical trial, they need to meet certain predefined criteria to be considered for participation. These are called inclusion criteria. They can include common characteristics, such as age, gender and ethnicity, as well as specific characteristics, like diagnosis and stage of disease. For reliable results and safety, it is important to determine inclusion criteria carefully.

Exclusion criteria are certain predefined characteristics that exclude people from taking part in a trial. These might include, for example, general characteristics, like age and gender, or other medical conditions. Exclusion criteria are used to narrow down the target population and thus make sure the trial is safe and the results are reliable.

Screening is a phase in early stages of a clinical trial during which participants visit the trial site and their eligibility for the trial is assessed in more detail. Depending on the trial, these assessments can include a physical examination, laboratory tests and diagnostic tests, such as imaging. The purpose of these assessments is to make sure the inclusion/exclusion criteria of the trial have been adhered to. At the screening visit, some baseline data is also collected. This means participant’s health data that is used as a reference point when assessing health changes that occur in the course of the trial. It is only after passing the screening stage that participants are enrolled in the trial.

The purpose of blinding is to make sure that trial participants, trial staff, or both, do not know which trial group (arm) a certain participant belongs to. A typical example of this is a trial that has one treatment arm and one placebo arm, and the participants do not know if they are receiving the active substance or the placebo. Blinding is used to make sure there is no bias in the trial.

In clinical trials, participants are often allocated to different groups (arms). One arm may, for example, receive the active substance, whereas the other arm receives the placebo. When participants are allocated to these arms randomly and by chance rather than choice, we talk about randomisation. This way, any participant can end up in any arm of the trial. For the reliability of the trial results, this is important.

When investigating and developing medicines, benefit-risk assessment is an integral part of the process. The purpose of the assessment is to determine whether medicine’s benefits outweigh its risks in a specific condition.

An adverse event is an unintended and harmful response to a medicinal product. Adverse events can be mild, moderate or severe. In terms of medicinal products, adverse events are also classified according to their frequency from very common to very rare and not known events.

Clinical trials are conducted in four different steps which are called phases. Phases describe the different stages of medicine development and each of them deals with different research questions.

Marketing authorisation is the approval given by a competent authority to market a certain medicine. The system of marketing authorisation and the assessments related to it are strict and regulated to make sure marketed medicines are sufficiently safe and effective.

Health-Related Quality of Life is a concept that aims to assess the medicine’s health benefits. This assessment is important in individual patient’s viewpoint but also generally as a means of measuring and evaluating treatment outcomes. Health-related quality of life reflects a person’s individual perception of how their disease or treatment affects their quality of life. Health-related quality of life includes physical, mental and social aspects related to a person’s disease or treatment and it is assessed using different metrics and questionnaires.

In clinical trials a sponsor is the entity that is responsible for initiating, managing, and often also funding a clinical trial. Often this entity is a pharmaceutical company, but in principle it can also be any other organisation, institution or government agency, such as a university or a university hospital.

Participants in each trial form its study population, i.e. it is the group of individuals in a study. In a clinical trial, the inclusion and exclusion criteria determine who will and will not be included in the trial.