How Is a Clinical Trial Planned and Carried Out? - Research Institute of the McGill University Health Centre
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Where do the ideas for trials come from?
In order to make a decision about whether to participate in a clinical trial, it helps to understand more about how trials are conceived and run. It is also important to know what happens once a trial is over.
The ideas for clinical trials often originate in the laboratory. Researchers develop a clinical trial protocol (the plan for a trial) after laboratory studies indicate the promise of a new drug or procedure. The first trials of a particular drug or procedure are focused on safety (phase I), and later trials focus on whether the drug or procedure is effective (phase II or phase III).
Every trial has a person in charge, usually a doctor, who is called the protocol chair or principal investigator. Phase I and phase II studies generally refer to the person in charge as the principal investigator. Phase III studies generally have a protocol chair, under whose direction multiple principal investigators carry out the protocol in participating sites. The protocol chair or principal investigator prepares a plan for the study, called a protocol. The protocol explains what the study will do, how it will be carried out, and why each part of the study is necessary. For example, the protocol includes
- the reason for doing the study
- how many people will be in the study
- who is eligible to participate in the study
- what study drugs participants will take, if any
- what medical tests they will have, if any, and how often
- what information will be gathered
Every doctor or research center that takes part in the trial uses the same protocol. This ensures that patients are treated identically, no matter where they are or if they are receiving treatment, and that information from all the participating centers (if there is more than one) can be combined and compared.
Clinical trials are sponsored by organizations or individuals who are seeking better treatments for a specific disease, or better ways to prevent or detect the disease.
Drug companies or companies that make diagnostic equipment (like X-ray machines) sponsor trials of their products, hoping to demonstrate that their products are safe and effective. The U.S. Food and Drug Administration (FDA) and Health Canada will only permit companies to sell a product after it has been proven safe and effective in clinical trials.
After a phase I or phase II trial is completed, the researchers look carefully at the data collected during the trial and decide whether to
- move on to the next trial with the treatment, or
- stop testing the treatment because it is not safe or effective
When a phase III trial comes to an end, the researchers must look at the data and decide if the results have medical importance. When the analysis of a phase I, phase II, or phase III trial is complete, the researchers will inform the medical community and the public of the study results.
In most cases, the results of trials are published in scientific or medical journals. To find out if the results of a study a volunteer participated in was published, it is best to:
- ask the doctor or nurse in charge of the treatment
- find out the official name of the study and search for it in the PubMed database of medical publications. In case of trouble locating the study or searching for it, the research librarian at a university or medical library may be able to help.
Most medical and scientific journals have in place a process of peer review, in which experts critique the report before it is published, to make sure that the analysis and conclusions are sound. Particularly important results are likely to be featured by the print or electronic media, as well as widely discussed at scientific meetings and by patient advocacy groups. Once an intervention is proven safe and effective in a clinical trial, it may become the new standard of practice. In this way the development of better interventions for prevention, treatment, or detection and diagnosis is an ongoing, continuous process that builds progressively on itself to improve the quality of health care and prevention tool available to us all.
The website of the National Cancer Institute (http://www.cancer.gov/clinicaltrials)