Clinical Research NetworksDeciding to take part in a clinical study is an important personal decision. This section aims to help you understand more about clinical research and how you can get involved.

A research study is a scientific process involving human volunteers (also called research participants) that is intended to improve or develop new methods of healthcare. A study can involve healthy participants with no pre-existing medical conditions but often pertain to participants with specific health conditions. Research studies are designed to answer specific questions on how to prevent, diagnose and treat a particular disease.

There are two main types of clinical studies: clinical trials (also called interventional studies) and observational studies.

What is a clinical trial?

In a clinical trial, participants receive specific interventions according to the research plan or protocol. The interventions may be medications, medical devices, procedures or changes to diet. Clinical trials are used to determine whether such interventions are both safe and effective.

What is an observational study?

In observational studies, study doctors assess health outcomes in groups of participants. The study may involve the collection of biological samples and the use of questionnaires or interviews to better understand the mechanisms of a disorder. Participants may receive interventions (which can include medical products such as medicines or devices) or procedures as part of their routine medical care, but participants are not assigned to specific interventions by the study doctor (as in a clinical trial). For example, investigators may observe a group of older adults to learn more about the effects of different lifestyles on cardiac health.

Who conducts clinical studies?

A clinical study is led by a principal investigator (lead study doctor), who is often a medical doctor. Clinical studies also have a research team that may include research scientists, doctors, nurses and other health care professionals.

Clinical studies can be sponsored or funded by pharmaceutical companies, academia, voluntary groups and other organisations. Physicians, health care providers, and other individuals can also sponsor clinical research.

Why participate?

People participate in clinical studies for a number of reasons. Participants can  play a more active role in their own health care and help others by contributing to medical research. In the case of a clinical trial, participants may access potential experimental medications or treatments before they may become available to the public.

Who can participate?

Study protocols include a set of predefined eligibility criteria outlining who can participate.  Research participants are evaluated for eligibility by their study doctor. This is an important principle of clinical research that helps to produce reliable results and to ensure it is considered safe for the participant to be included. The criteria used are based on factors such as age, gender, the type and stage of disease, previous treatment history and other medical conditions. It is important to note that inclusion and exclusion criteria are not used to reject people personally; they help ensure that researchers will be able to answer the questions they plan to study.

How are participants protected?

All clinical research studies undertaken in Ireland must comply with the highest national and international ethical standards and relevant regulations.

To take part in a clinical study every participant must voluntarily sign a consent form that explains the research study, the foreseeable risks, potential benefits, other appropriate treatment options and where to find further information. It also explains one’s rights as a participant in the study. If at any time a participant is not comfortable with the study, they have the right to withdraw. Confidentiality of records and data are also assured.

Commonly used terms

Patient information leaflet (PIL): For each clinical study, there is a PIL which explains why you have been asked to take part, what the study is about and what it will involve. Also included are the potential risks and known side effects as well as the alternative treatment available should you choose not to participate. The purpose of the PIL is to provide you with all information necessary to decide if you wish to take part or not. Your participation in a clinical study is always voluntary, and deciding not to take part will not affect your continued medical care. Before you can be enrolled into a research study, you must read the PIL and give written informed consent. After signing, you are still free to withdraw from the study at any time.

Informed consent form (ICF): The ICF is a document that is completed by the participant and a member of the research team. By signing the ICF the participant confirms that he/she understands the information regarding the study (this is usually given in the form of the Patient Information Leaflet), has had the opportunity to ask questions and agrees on a voluntary basis to take part. A copy of the ICF is given to the participant along with the PIL to keep. If new information arises during the study, the participant will be informed by the research team, and may be asked to sign a new ICF.

Randomised trial: This is a process by which participants are assigned to a treatment group in a trial. Participants are randomly allocated to one or other of the different treatment groups in the trial, there is no identifiable pattern, therefore no one can predict which treatment the participant will receive. Randomisation is performed to prevent bias in the trial, by ensuring balance across the groups.

Blinded trial: In a blinded trial, participants are not aware of which treatment group they have been assigned to. In the case of a double-blind trial neither the participant nor the research team are aware of the treatment group assigned. Blinding is used to prevent bias.

Placebo controlled: A study may include a ‘dummy’ treatment group which is matching in appearance to the active treatment. Participants will be randomly assigned to receive the placebo (also known as a sugar pill or dummy drug) or the active treatment.

Bias: Bias is when prejudices lead to incorrect conclusions about the effects of treatment. It is really important to avoid bias in health research, as it can distort the results and could lead to unsafe or inefficient treatments being uses, or useful treatments being overlooked. Investigators try to avoid bias by using randomisation and blinding.

Clinical trial phases: Clinical trials are classified into four phases according to which stage of the development process the trial is in.

  • Phase I – A experimental drug or treatment is tested on a small group of people approximately 20-80 for the first time. The purpose is to evaluate safety, to identify the correct dose, and identify any side effects.
  • Phase II –A slightly larger group of participants are used to further test for safety and to examine efficacy (i.e. how/if the treatment works). Often participants may be assigned to the active treatment/drug or a matching placebo.
  • Phase III – These are usually large global trials performed to confirm efficacy (i.e how/if the treatment works), to compare to the standard treatment or drug and to monitor for side effects. Information from these trials are often used to support marketing approval for the drug or treatment to be used.
  • Phase IV – These studies are conducted following marketing approval and are primarily to obtain further information regarding the safety and benefits of treatment.

Sources of further information

If you are interested in becoming a participant in research, please consult with your own doctor in the first instance. You may also wish to contact your patient representative organisation or publically available clinical research registers. We have listed some relevant websites for your information below.

  • Check out the Irish Platform for Patient Organisations, Science and Industry (IPPOSI) websites: and The websites and associated documents are part of an IPPOSI information campaign intended to advise the public about taking part in clinical trials, including information specifically tailored for different age groups of children.
  • The European Medicines Agency has a publicly accessible database of drug clinical trials:
  • The United States authorities have created a website where trials conducted around the world can be found:

Please note that, in accordance with ethical standards for clinical research, HRB NCTO is not in a position to provide advice or consult with individual patient’s regarding participation in specific clinical studies.