Definition: Defining the Meaning of Clinical Trial
Clinical trials are defined as research studies that test how well new medical approaches work in people. Each study answers scientific questions and tries to find better ways to prevent, screen for, diagnose, or treat a disease. Clinical trials may also compare a new treatment to a treatment that is already available. Such prospective biomedical or behavioral research studies on human participants are designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel vaccines, drugs, dietary choices, dietary supplements, and medical devices) and known interventions that warrant further study and comparison. Clinical trials used in drug development are sometimes described by phase. These phases are defined by the Food and Drug Administration (FDA).
Clinical trials are conducted to allow safety and efficacy data to be collected for new drugs or devices. These trials can only take place once satisfactory information has been gathered on the quality of the non-clinical safety, and Health Authority/Ethics Committee approval is granted in the country where the trial is taking place.
During the clinical trial, the investigators: recruit patients with the predetermined characteristics, administer the treatment(s), and collect data on the patients' health for a defined time period. These data include measurements like vital signs, amount of study drug in the blood, and whether the patient's health gets better or not. The researchers send the data to the trial sponsor who then analyzes the pooled data using statistical tests.
The U.S. National Institutes of Health (NIH) organizes trials into five different types:
- Prevention trials: look for better ways to prevent disease in people who have never had the disease or to prevent a disease from returning. These approaches may include medicines, vitamins, vaccines, minerals, or lifestyle changes.
- Screening trials: test the best way to detect certain diseases or health conditions. Diagnostic trials: conducted to find better tests or procedures for diagnosing a particular disease or condition.
- Treatment trials: test experimental treatments, new combinations of drugs, or new approaches to surgery or radiation therapy.
- Quality of life trials: explore ways to improve comfort and the quality of life for individuals with a chronic illness (a.k.a. Supportive Care trials).
- Compassionate use trials: provide experimental therapeutics prior to final FDA approval to patients whose options with other remedies have been unsuccessful. Usually, case by case approval must be granted by the FDA for such exceptions.
Clinical trials involving new drugs are commonly classified into four phases. Each phase of the drug approval process is treated as a separate clinical trial. The drug-development process will normally proceed through all four phases over many years. If the drug successfully passes through Phases I, II, and III, it will usually be approved by the national regulatory authority for use in the general population. Phase IV are 'post-approval' studies.
Participating in a clinical trial
Phase 0 and Phase I drug trials seek healthy volunteers. Most other clinical trials seek patients who have a specific disease or medical condition.
Locating Clinical Trials
Depending on the kind of participants required, sponsors of clinical trials use various recruitment strategies, including patient databases, newspaper and radio advertisements, flyers, posters in places the patients might go (such as doctor's offices), and personal recruitment of patients by investigators.
Volunteers with specific conditions or diseases have additional online resources to help them locate clinical trials.
Steps for Clinical Trial Volunteers
Before participating in a clinical trial, interested volunteers should speak with their doctors, family members, and others who have participated in trials in the past. After locating a trial, volunteers will often have the opportunity to speak or e-mail the clinical trial coordinator for more information and to answer any questions. After receiving consent from their doctors, volunteers then arrange an appointment for a screening visit with the trial coordinator.
Due to the sizable cost a full series of clinical trials may incur, the burden of paying for all the necessary people and services is usually borne by the sponsor who may be a governmental organization, a pharmaceutical, or biotechnology company. Since the diversity of roles may exceed resources of the sponsor, often a clinical trial is managed by an outsourced partner such as a contract research organization.
For safety reasons, many clinical trials of drugs are designed to exclude women of childbearing age, pregnant women, and/or women who become pregnant during the study. In some cases the male partners of these women are also excluded or required to take birth control measures.
You can search for current U.S. clinical trials for a range of conditions at https://clinicaltrials.gov/ct2/search
Quick Facts: Clinical Trial
- The British Medical Research Council officially recognized the importance of clinical trials from the 1930s.
- Informed consent is a legal process in which a recruit is instructed about key facts before deciding whether to participate.
- The first randomized curative trial was carried out at the MRC Tuberculosis Research Unit by Sir Geoffrey Marshall (1887 - 1982).
- For chronic conditions such as cancer, it takes months, if not years, to see if a cancer treatment has an effect on a patient.
- A clinical trial protocol is a document used to define and manage the trial. It is prepared by a panel of experts. All study investigators are expected to strictly observe the protocol.
- Some clinical trials involve healthy subjects with no pre-existing medical conditions. Other clinical trials pertain to patients with specific health conditions who are willing to try an experimental treatment.
- All studies involving a medical or therapeutic intervention on patients must be approved by a supervising ethics committee before permission is granted to run the trial.
- For safety reasons, many clinical trials of drugs are designed to exclude women of childbearing age, pregnant women, and/or women who become pregnant during the study.
- Clinical trials involving new drugs are commonly classified into four phases. Currently, some Phase 2 and most Phase 3 drug trials are designed as randomized, double-blind, and placebo-controlled.
- Before participating in a clinical trial, interested volunteers should speak with their doctors, family members, and others who have participated in trials in the past.