Clinical trials are research investigations that involve people like you and me. They are research studies which involve testing novel medical interventions, strategies, devices or treatment on volunteers in a bid to detect, manage, treat or prevent several medical conditions and diseases.1 It could involve studying the response of the volunteers to the novel intervention and observing for side effects. The aim of which is to determine the safety and efficacy of the intervention, and compare its effectiveness to other available interventions.

Clinical trials can also be carried out to test new methods of using or combining available interventions, and likewise to study how other factors like pharmacogenetics, dietary changes, etc. can affect the overall outcome of drug therapy. In general, clinical trials increase medical knowledge and aid the decision-making process in health care by providing reliable data.2

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How Do Clinical Trials Work?

In a bid to ensure the safety of the participants3, the first phase of clinical trials involves the administration of a low dose of the drug to a small group of people. This is to ascertain that the new intervention does not produce any unwanted side effects in humans.

Clinical research involving humans take place in the final stages of a lengthy, comprehensive and systematic research process, and follow stringent standards and guidelines. At ClinicalMatch, these standards and guidelines 4 are sternly adhered to, with the aim of:

  • Protecting the participants
  • Providing accurate and reliable results

The research process commences in a laboratory, which is where novel ideas and interventions are tested. After animal studies, experimental interventions that are most promising are moved to the clinical trials stage, where they would be tested in human subjects. The new intervention is usually compared against the control, which can be a placebo or an already established intervention.

There are a number of aspects involved in the planning, running and follow up of a clinical trial.

The Clinical Trial Protocol

Clinical trials follow a protocol, which is a plan that explains the objectives, design, procedures, scientific background and relevant statistical information of the study. The trial protocol describes:

  • The number of people that would participate in the trial
  • Those that are eligible
  • The tests or procedures involved
  • The type of data to be collected
  • Details about the treatment plan

The Experimental and Control Groups

The efficacy of a novel intervention is determined by comparing it to an established intervention, placebo or other standard care which could be non-interventional. In a clinical trial, the participants are segmented into two groups:

  • The experimental group, and
  • The control group

The experimental group is the group that would be given the novel intervention, which is being accessed. In contrast, the control group is the group that would be given established intervention, placebo or other standard care. On comparison, the difference in the results obtained from the two groups must be sufficient to prove that such a distinction did not occur by chance.

A new intervention can be compared with an established intervention in other to determine which of them works better. A new intervention can also be compared with a placebo to determine if such an intervention is effective.

Number of Participants Involved in a Clinical Trial

The effect of an intervention may vary between different populations. Thus, to ensure that these differences are real and did not occur by chance, promising interventions are tested on a large number of people, and the results are statistically analyzed. On a general note, the number of people that participate in a clinical trial depends on the phase of the trial.

Avoiding Bias in a Clinical Trial

In clinical trials, the researchers must take measures to ensure that Bias is avoided. Such measures include randomization and blinding.5 Bias can affect the results of a trial, causing the results to be unreliable. Randomization is most times, done by a computer. It ensures that the differences observed between comparison groups i.e. the experimental and control groups, are not due to the participant’s pre-existing differences. Blinding also referred to as masking, helps avoid Bias by ensuring that the participants, and in some cases, the researchers are not informed about those that are receiving the novel intervention and those that are not.

Who Can Participate in a Clinical Trial?

There are different types of clinical trials and based on this fact; basically, anyone can participate in clinical trials.

Types of Clinical Trials

According to Wikipedia6, clinical trials can be classified based on the research objective or based on their purpose. Based on the research objective, we have two types:

  • Observational Study
  • Interventional Study

While based on their purpose, there are:

  • Screening Trials
  • Prevention Trials
  • Diagnostic Trials
  • Treatment Trials
  • Quality of Life Trials
  • Adaptive Trials
  • Epidemiological Trials, etc.

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Inclusion and Exclusion Criteria in Clinical Trials

Due to the variety of clinical trial types, almost anyone can participate. However, for all clinical trials, there are guidelines as to who can participate.7 These guidelines are referred to as inclusion and exclusion criteria8. These criteria are determined by the type of clinical trial and are based on factors like age, gender, previous medical history, type and stage of a disease condition, amongst others.

Inclusion criteria refer to the characteristics the prospective subject must possess to be allowed to participate in the trial. The eligibility criteria are defined in the clinical trial protocol and determine those who can be a part of the clinical trial.9 While some trials require healthy volunteers, some others require patient volunteers. There are also clinical trials that require healthy and patient volunteers. Typical examples of inclusion criteria include:

  • Having a particular type and stage of illness
  • Being perfectly healthy, with the absence of any medical conditions

Exclusion criteria, on the other hand, are characteristics that rule out or disqualify prospective subjects from being part of a clinical trial. Possible exclusion criteria include:

  • Inability to give informed consent
  • Potential allergy to the intervention
  • If the participant is receiving another treatment that might affect the result of the trial.

The inclusion and exclusion criteria for a clinical trial are intended to ensure the safety of the participants, justify the appropriateness of the subjects, minimize volunteer withdrawals during the trial and ensure the overall success of the clinical trial.

Rest assured, ClinicalMatch helps you find the perfect clinical trials to participate in, and the right treatment regardless of the condition.


  1. What is a Clinical Trial, adapted from
  2. How do Clinical Trials Work and Who can Participate, adapted from
  3. Is it Safe to Participate in a Clinical Trial, adapted from
  4. Clinical Trials and Human Subjects, adapted from
  5. Statistics in clinical trials: Bias, adapted from
  7. Who can be part of clinical trial, adapted from
  9. Clinical Trials, adapted from

Published by Anu bhargava

I am Ayesha Bhargava is a SEO or SMO Executive work with Nilank Technologies. i love Fashion, Shopping and Discover New Things.

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