A clinical trial is a research study, the outcome of which is designed
to answer specific questions about new therapies, new ways of using existing
treatments, as well as better ways to prevent, diagnose or treat diseases.
Trials are used to investigate the efficacy, safety, tolerability and cost-effectiveness
of a treatment. Trials may also be used to demonstrate a drug’s advantages
over other treatments and identify the correct dosage for treatments. The
treatment is tested on a sample of patients selected from a specific population.
Why do we need clinical trials?
A clinical trial is one of the final stages of a long research process. Researchers
test new therapies or procedures in a laboratory and in experimental studies.
The treatments with the most promising laboratory results are moved into clinical
trials. Carefully conducted clinical trials are the fastest and safest ways to
find treatments that work in people.Clinical trials require huge financial investments
as well as committed resources. To adequately evaluate a treatment, the duration
of some trials may run into years, for example the EUROPA study, which was launched
in 1997 and concluded in 2003.
What are the types of clinical trials?
Treatment trials are
used to test new treatments, combinations of treatments, or new approaches to
Prevention trials may
involve medicines, vitamins, minerals, vaccines, or lifestyle changes. These
trials are designed to find better ways of preventing disease
in people who may be at risk of a disease, or wish to prevent the return of a
Screening trials are
designed to find the best detection procedure for a disease
Quality of life trials
usually involve people who are chronically ill and explore ways to improve different
quality of life parameters, such as sleep, mobility
and ability to work.
What are the phases of clinical trials?
Clinical trials are conducted in phases, with each phase providing the answers
to different questions.
Phase I trials usually involve a group of less than 100 healthy volunteers who
will be given a new drug or treatment. The outcome of this trial will determine
a safe dosage range, the best dosage method, evaluate safety and identify possible
Phase II trials involve hundreds of participants suffering from a condition relevant
to the treatment. These trials further evaluate efficacy and safety of a study
drug as well as identifying dose selection. The outcomes of phase II trials will
determine the feasibility of evaluations for larger phase III trials
Phase III trials involve thousands of participants suffering from a condition
relevant to the treatment and are designed to confirm efficacy, monitor side
effects, compare it to standard treatments and collect any further information
to assist in the correct usage of the drug. These trials may be multinational
and involve many test centres. The EUROPA trial is the largest morbidity-mortality
trial ever conducted with an antihypertensive agent specifically in all patients
with coronary artery disease. It involved 12,000 patients and spanned 24 countries
Phase IV trials are usually conducted by the manufacturer after the product is
approved and involve tens or hundreds of thousands of participants suffering
from a condition relevant to the treatment. Additional information, including
the drug’s risks, benefit and optimal use will be evaluated
What is a blind or masked trial?
In most clinical trials, a ‘treatment group’ will receive the study
drug and a ‘control group’ will receive placebo or standard treatment.
In a blinded or masked study, participants are not aware which group they are
in. Physicians may also be blinded to the treatment a patient is receiving. This
is called a ‘double-blind trial’, and is designed to prevent study
bias, as some patients and physicians may expect better results on a study drug
and therefore report hopeful signs.
Why are patients randomised?
In trials involving both treatment and control groups, participants may be assigned
to either group by chance. This process is called randomisation and is used to
avoid study bias and ensure that study results accurately reflect the treatment
Who sponsors clinical trials?
Sponsorship may come from a variety of organisations or individuals such as
physicians, medical institutions, foundations, voluntary groups, pharmaceutical
companies and national health institutes. Trials can take place in a variety
of locations, such as hospitals, universities, GP surgeries and community
What is a protocol?
A protocol is a study design or blueprint on which all clinical trials are based.
All information concerning the purpose, design, conduct and planned analysis
of the trial are included. A protocol will describe what types of people may
participate in the trial, the test schedule, procedures, medications, dosages
and the length of the study.
What is a placebo?
A placebo is an inactive pill, liquid, or powder that has no treatment value.
Placebos are often used as a comparison with experimental treatments to assess
the treatment’s effectiveness. A placebo medication will resemble an active
treatment in size and composition. In many diseases, the act of ‘taking
a pill’ or being involved in a trial may significantly improve symptoms.
This is called the ‘placebo effect’. A comparison against a placebo
is clinically essential to assess the efficacy and tolerability of the trial
medication against the background placebo level of response.
What is a control or control group?
A control is the standard by which experimental observations are measured. In
clinical trials, a control group may be given a traditional treatment or a placebo.
In the EUROPA trial, the study group received perindopril 8mg/day in addition
to existing treatments, while the control group received a placebo in addition
to existing medications.