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Clinical Trials


Clinical trials are research studies performed in people that are aimed at evaluating a medical, surgical, or behavioural intervention. They are the first way that researchers determine if a replacement treatment, sort of a new drug or diet or medical device is safe and effective in people.

Clinical Trials

The purpose of clinical trials is to answer scientific questions. Therefore, these studies follow strict, scientific standards which protect patients and help produce reliable clinical test results. Clinical trials are one among the ultimate stages of an extended and careful research and development process. The process often begins during a laboratory, where scientists first develop and test new ideas.

Clinical trials related to drugs are classified into four phases. The trials at each phase have a special purpose and help scientists answer different questions:

  • Phase I: These are the trials test an experimental drug, vaccine or device in a small group of people to evaluate the safety, possible side effects, and to determine how the drug should be used or delivered.
  • Phase II: These are the trials involve more people than Phase I and they are designed to assess the safety and efficacy of an experimental treatment. This phase can last for several years.
  • Phase III: These are the trials are usually large studies with many participants. This phase compares the experimental drug or vaccine to a placebo or standard treatment, to gauge safety and efficacy. Some side effects that weren’t identified in phase II clinical trial could also be identified during a phase III clinical trial because more people are evaluated. The regulatory health authority, such as the U.S. Food and Drug Administration, will consider the results of clinical trials up to and including phase III clinical trial trials when determining whether to approve a replacement drug or vaccine.

Eligibility criteria may include:

  • Targeted disease or disorder
  • Indication past history
  • Being in a certain age group
  • Medical history
  • Current health status

Criteria like these help to scale back the medical differences among people participating within the clinical test in order that researchers are often more certain that the results are due to the treatment being tested and not to another reason.

In addition, because some people that want to require part during a clinical test have health problems outside of the disease being studied which might be suffering from the treatment being evaluated, anyone curious about joining a clinical test will receive medical tests to verify their eligibility.

Clinical trial benefits & risks

The potential benefits of participating during a clinical test may include the following:

  • Access to new treatments which are not available outside the clinical-trial setting
  • Treatment or medication that may be more effective than the standard approach
  • Close monitoring, advice and support by a research team of doctors and other health care professionals who understand disease or condition
  • The opportunity to get the beenefit from a new method understudy
  • The chance to play an active role in your own health care and gain a greater understanding of your disease or condition

Special Concerns in Clinical Trials:

  • Protection of Trial Subjects. Informed consent prior to participation. Review by the ethics committee. Compliance with the trial protocol.
  • Quality of the Data. Reproducibility and comparability. Validity and credibility. Representativeness and generalizability.
  • Transparency of Trial Conduct.

Types of Clinical Trials:

There are two main sorts of trials or studies – interventional and observational.

Interventional trials: The aim to find out more about a particular intervention, or treatment. People participating are put into different treatment groups, in order that the research team can compare the results.

Observational studies: The aim to find out what happens to people in different situations. The research team observe the people taking part, but they don’t influence what treatments people have. The people participating aren’t put into treatment groups.

There are different types of trials within these two groups.

Pilot studies and feasibility studies

Pilot studies and feasibility studies are small versions of studies which are sometimes done before an outsized trial takes place.

Feasibility studies are designed to see if it is possible to do the main study. They aim to find out things such as whether patients and doctors are happy to take part, and how long it might take to collect and analyse the information. They don’t answer the main research question about how well a treatment works, for example.

Pilot studies are the small scale of the study. Pilot studies help to test that all the main parts of the study work together. They may also help answer the research question. Sometimes the research team include the knowledge collected during the pilot study within the results of the most study.

Prevention trials – treatment can help prevent cancer. The people taking part don’t have cancer.

These trials can be for the general population or for people who have a higher than normal risk of developing certain cancer. This could include people with a family history, for example.

Screening trials:

Screening means testing people for the first signs of cancer before they need any symptoms. As with prevention trials, screening trials are often for the overall population. Or they will be for a gaggle of individuals who have a better than normal risk of developing particular cancer. Researchers may plan screening trials to ascertain if new tests are reliable enough to detect particular sorts of cancer. Or they may try to find out if there is an overall benefit in picking up cancer early.

Treatment trials:

Treatment trials are done in stages, called phases. The early phases aim to find out more about the safety and side effects of new treatments. Later phases aim to ascertain if a replacement treatment works better than the present treatment. For trials that compare two or more treatments, the people participating are put into a treatment group randomly. Randomised trials are the best way to get reliable information about how well a new treatment works. We have more information about randomisation.

Multi-arm multi-stage (MAMS) trials:

A multi-arm trial may be a trial that has several treatment groups (arms) also because of the standard treatment group (the control group).

Multi-arm multi-stage (MAMS) trials have an equivalent control group all the way through. But the opposite treatment groups can change because the trial goes on.

The research team may decide to stop recruiting people to a particular group. This could be because they have enough people to start looking at the results. Or because early results show the treatment isn’t working as well as they’d hoped.

And they may add new treatment groups as new drugs become available to seem at. This means they don’t have to design and launch a brand new trial each time they want to research a new treatment. So it helps get results quicker.

The Stampede trial for prostatic adenocarcinoma is an example of a MAMS trial.

Observational studies:

Cohort studies, case-control studies and cross-sectional studies are all types of observational studies.

Cohort studies:

A cohort is a group of people, so cohort studies look at groups of people. A cohort study follows the group over a period of time.

A research team may recruit people that don’t have cancer and collect information about them for variety of years. The researchers see who in the group develops cancer and who doesn’t. They then look to see whether the people who developed cancer had anything in common. Cohort studies are very useful ways of finding out more about risk factors. But they are expensive and time-consuming. They can be used when it wouldn’t be possible to test a theory in any other way.

Case control studies:

Case-control studies work the opposite way to cohort studies. The research team recruits a group of people who have a disease (cases) and a group of people who don’t (controls). They then reminisce to ascertain what percentage of people in each group were exposed to a particular risk factor.

Researchers want to make the results as reliable as possible. So they try to make sure the people in each group have the same general factors such as age or gender. Case-control studies are useful and they are quicker and cheaper than cohort studies. But the results may be less reliable. The research team often believe people thinking back and remembering whether or not they were exposed to a particular risk factor or not. But people may not remember accurately, and this can affect the results.

Another issue is that the difference between association and cause. Just because there is an association between a factor and a disease, it doesn’t mean that the factor causes the disease.

For example, a case-control study may show that people with a lower income are more likely to develop cancer. But it doesn’t mean that the level of income itself causes cancer. It may mean that they have a poor diet or are more likely to smoke.

Cross sectional studies:

Cross-sectional studies are carried out at one point in time, or over a short period of time. They determine who has been exposed to a risk factor and who has developed cancer, and see if there’s a link. Cross-sectional studies are quicker and cheaper to do. But the results can be less useful. Sometimes researchers do a cross-sectional study first to find a possible link. Then they go on to do a case-control or cohort study to look at the issue in more detail.

Informed Consent Form:

Informed consent involves providing a possible participant with: adequate information to permit for an informed decision about participation within the clinical investigation. facilitating the potential participant’s understanding of the information.

Endpoint in Clinical Trials:

A clinical test might use a clinical endpoint or a surrogate endpoint. A clinical endpoint is an outcome that represents direct clinical benefit, such as survival, decreased pain, or the absence of disease.


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