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A Simple Guide to Clinical Trials

June 25, 2014 Alpha1 Admin Comments Off

A Simple Guide to Clinical Trials

The Medical Research Charities Group (MRCG) is an umbrella group of medical research and patient support charities, many of which are involved in with rare diseases. In order to support patients and those interested in medical research. MRCG has compiled a “Plain English Guide” to the common terms used in clinical trials.

Adverse reaction (Adverse event/side effect):

An unwanted effect caused by the administration of drugs. Onset may be sudden or develop over time.


  1. Information gathered at the beginning of a study from which variations found in the study are measured.
  2. A known value or quantity with which an unknown is compared when measured or assessed.
  3. The initial timepoint in a clinical trial, just before a participant starts to receive the experimental treatment which is being tested. At this reference point, measurable values such as those relating to the strength of the immune system are recorded. Safety and efficacy of a drug are often determined by monitoring changes from the baseline values.


When a point of view prevents impartial judgment. In medical science it is important to avoid bias affecting the interpretation of data. In clinical studies, bias is controlled by blinding (see Blind below) and randomization.


A clinical trial is “Blind” if participants are unaware on whether they are in the experimental or control arm of the study; also called masked.


Refers to a group of subjects who have some defining characteristic in common and who remain part of this group over an extended period of time. The common characteristic in a medical cohort may be a risk factor for a disease or health effect.


Pertaining to or founded on observation and treatment of participants, as distinguished from theoretical or basic science.

Clinical investigator:

A medical researcher in charge of carrying out a clinical trial.

Clinical trial:

A clinical trial is a research study to answer specific questions about vaccines or new therapies or new ways of using known treatments. Clinical trials are used to determine whether new drugs or treatments are both safe and effective. Carefully conducted clinical trials are the fastest and safest way to find treatments that work in people. Trials are in four phases:
  • Phase I tests a new drug or treatment in a small group;
  • Phase II expands the study to a larger group of people;
  • Phase III expands the study to an even larger group of people;
  • Phase IV takes place after the drug or treatment has been licensed and marketed.

Control group:

The standard against which experimental observations are evaluated. In many clinical trials, the control group receives a placebo treatment.


The Food and Drug Administration is the regulatory body in the United Stated with responsibility for protecting the public health by assuring the safety, efficacy, and security of human and veterinary drugs; biological products; medical devices; food supply; cosmetics; and products that emit radiation.

Peer review:

Review of a scientific paper or clinical trial by experts in the field. These experts review the paper or trials for scientific merit, participant safety and ethical considerations.


The processes (in a living organism) of absorption, distribution, metabolism and excretion of a drug or vaccine.

Placebo effect:

A physical or emotional change, occurring after a substance is taken or administered, that is not the result of any special property of the substance. The change may be beneficial, reflecting the expectations of the participant and, often, the expectations of the person giving the substance.


A study plan on which all experimental studies or clinical trials are based. A protocol for clinical trials is carefully designed to safeguard the health of the participants as well as answer specific research questions. A protocol describes what types of people may participate in the trial; the schedule of tests, procedures, medications, and dosages; and the length of the study. While in a clinical trial, participants following a protocol are seen regularly by the research staff to monitor their health and to determine the safety and effectiveness of their treatment.


An adverse effect produced by a drug that is detrimental to the participant’s health. CLINICALTRIALS.IE Another excellent resource is the IPPOSI-led website www.clinicaltrials.ie which was launched in 2012.  This website with age appropriate content and the associated documents are part of an IPPOSI information campaign intended to advise the public about clinical trials. From the research which IPPOSI has undertaken, we know that providing information increases the positive attitude which people have about participating in a clinical trial. Increasing the willingness of people to participate in such research will inevitably help to develop new treatments and therapies for patients.