Clinical trials play a hugely important role in advancing medical discoveries and improving patient care – as do the volunteers who take part.
According to ClinicalTrials.gov, more than 476,000 clinical studies were running worldwide in 2023, compared to just over 2,100 back in 2020. This means significantly more life-changing discoveries are being tested, and there’s a higher demand than ever for clinical trial participants.
We take a detailed look at these vital studies, giving you a thorough understanding of what they are, the various types, the benefits and risks, and how you can get involved.
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What is a clinical trial?
Clinical trials are research studies that examine the effectiveness and safety of new medical interventions, such as drugs, treatments, procedures, or devices. They play a vital role in furthering medical knowledge and enhancing patients’ lives.
These valuable trials follow very strict protocols, and are carefully designed to answer specific research questions within a controlled environment. Participants might include healthy individuals, people with existing conditions, or both.
What is the difference between clinical research and clinical trials?
Clinical research is the broad term for all scientific medical studies involving human participants. They include observational studies, outcomes research, interventional studies (which may involve clinical trials), epidemiological studies, and behavioral studies.
Clinical trials are a specific type of clinical research which follow a structured process to test medical interventions on human participants. All clinical trials are a form of clinical research, but not all clinical research involves clinical trials.
What is the purpose of clinical trials?
Clinical trials are vitally important, as they aim to determine the effectiveness and safety of new medical interventions that could change people’s lives. However, they may also have other objectives, including:
- discovering how to prevent health problems
- researching how to diagnose diseases early
- making current treatments more effective and easier to use
- finding out how existing interventions can have fewer side effects
- testing the effectiveness of treatments in a different populations
- enhancing quality of life for people with chronic or terminal conditions
- examining the roles of caregivers or support groups
Who runs clinical trials?
Clinical trials usually have a sponsor organization which designs and oversees the study. In some cases, this could be the pharmaceutical company that discovered the intervention. In other cases it might be a university or hospital.
A doctor, known as the principal investigator (PI), will lead the trial and make all study-related medical decisions. They are assisted by a study coordinator who guides the participants through the study.
How do researchers decide who will participate?
Different trials have different participant criteria, and this will be clearly defined in the study protocol. These exclusion and inclusion criteria ensure the trial only includes participants who can provide meaningful data.
If you’re excluded from one trial, it doesn’t necessarily mean you will be excluded from another as they are all unique.
Inclusion criteria
Inclusion criteria include age, race, gender, and ethnicity. Some trials test new medications for a certain disease, and will therefore only include people with that condition. In some cases, the severity of the disease will also be specified.
Exclusion criteria
Certain pre-existing conditions can exclude you from specific clinical trials – as can taking some medications which could interact with the investigational treatment.
Lifestyle choices, such as smoking and alcohol consumption, might also exclude you from a trial, as could pregnancy and breastfeeding, in order to protect the child.
How long do clinical trials take?
The duration of a clinical trial depends on the type of study it involves, what it hopes to achieve, how complex it is, and what phases you’re involved in. For example, a phase 1 trial can last several months to a year, whereas a phase 3 trial could go on for several years.
It’s also important to keep in mind that a clinical trial is likely to involve more time and attention than standard treatments, involving visits to the study site, and various tests, procedures, hospital stays, or complex dosage schedules.
The research team should be able to indicate how long you’re expected to be involved in a trial.
Types of clinical studies
Several different types of clinical studies are used by research teams, although not all of these are strictly categorized as 'clinical trials’. An observational study, for example, is one such type. Despite this, understanding these various forms of clinical studies is important, as they often contribute to a larger research project that may be in line with a clinical trial.
The research designers will use the most appropriate clinical study for the purposes and objectives of the tests being conducted. As such, they may select a clinical trial, or decide on a different type of study.
Interventional studies
These studies assess the safety and effectiveness of new tests or treatments. They might include drugs or drug combinations, surgical procedures or devices, or new methods of using existing treatments.
Prevention trials
These clinical trials investigate ways to prevent a condition from occurring, or from returning to a patient who had it in the past.
Treatment trials
These trials test new treatments, drug combinations, or approaches to surgery to discover new or more effective ways of treating a specific condition.
Screening trials
Screening trials assess how effective devices, techniques, or procedures are at detecting a disease of condition – usually before symptoms appear.
Observational studies
During observational studies, a sample of the population is observed and data is taken, but no intervention, such as medication, is given to them. Whilst they aren’t strictly clinical trials, these studies are an important part of clinical research.
Medical records research
This research involves studying the medical records of large groups of people over long periods of time. Researchers can then assess how a particular disease or condition progresses, and what interventions proved to be most effective at treating it. Again, this is a clinical study rather than a clinical trial.
How does grouping work in clinical trials?
When assigning you to a role in a clinical trial, researchers will either use a randomized or a non-randomized approach.
Randomized clinical trials (RCT)
Randomization in clinical trials involves assigning participants to treatment and control groups blindly, so everyone has an equal chance of being assigned to any group. Tools such as computer generated sequences, random number selection, and closed envelopes can be used as part of the process.
Non-randomized controlled trials
During non-randomised controlled trials, the principal investigator will allocate participants to specific groups. This design is used when random allocation could reduce the intervention’s effectiveness.
How are clinical trials conducted?
Clinical trials are carefully conducted in a systematic way to ensure the reliability of the results. Your safety and wellbeing are the top priority throughout, and you will have regular opportunities to report any concerns about the treatment being administered or the trial itself.
Before the trial begins
At the start of the process, you’ll be screened to ensure you qualify for the trial. If you’re accepted, the research staff will explain the study in detail, answer any questions, and gather additional information about you.
If you agree to take part, you then sign an informed consent form, confirming that you understand your role as a participant, and the potential risks and outcomes.
You may then be asked to attend a ‘baseline’ visit, during which the researchers conduct a few initial cognitive and/or physical tests.
If you’re testing an intervention, you are likely to be randomly assigned to either a treatment group or a control group. You won’t be aware of which you belong to as this can result in bias, generating unreliable results.
During the trial
The treatment group receives the intervention, while the control group is given either an existing treatment, or a placebo.
You can expect to visit the research site at regularly scheduled times to undertake physical, cognitive, or other assessments, and to have discussions with the researchers. Data will be collected from these examinations, and your safety and wellbeing will be carefully monitored.
It’s important to follow all the procedures for the duration of the study, and report any concerns or issues to the researchers.
Phases of clinical trials
There are several different clinical trial phases, and each serves a different purpose. The US Food and Drug Administration (FDA) usually stipulates that phase 1, 2, and 3 trials are completed before a drug can be approved for general use.
Phase 1 trial
During a phase 1 trial, researchers test a medical intervention on a small group – usually 20–80 people – to assess its safety, any side effects, and the optimum dosage. This is the first time it will be trialed in human participants.
If testing a drug, the researchers will begin with small doses, and gradually increase them over time if they determine it is safe to do so.
Phase 2 trial
Phase 2 trial trials typically include around 100–300 participants and are designed to determine the effectiveness of an intervention, as well as its safety. As such, this phase usually involves people who have the disease or condition the treatment was designed for.
Phase 3 trial
Phase 3 trials can involve several hundred to several thousand participants, and usually last a year or more. They are designed to gain additional information about interventions that have passed phases 1 and 2. They carefully examine the effects of different dosages in various populations, and compare them with other treatments.
If a drug or device passes this trial phase, a New Drug Application (NDA) can be submitted to the FDA, with the likelihood of approval exceeding 80%.
Phase 4 trial
Once a new intervention is approved and licensed, and it’s available on prescription, a phase 4 trial might be undertaken. This examines it being used in practice amongst large, diverse populations – although not all treatments undertake this phase.
The aim of this phase is to assess the effectiveness and side effects of treatments after they've been in use for significant timescales.
What about pre-clinical studies?
Preclinical research takes place before a trial on human participants begins. It gathers information about safety, efficacy, and the potential risks of an intervention, determining whether it can move onto human testing.
What happens after a clinical trial has ended?
Once a clinical trial has ended, the data is carefully analyzed, and decisions are made about next steps – which might include further testing.
In the US, if a new drug or treatment is proven to be safe and effective, researchers will submit the results to the FDA so they can decide whether to approve it for general use.
The results from clinical trials are usually published in peer-reviewed scientific journals – which means experts review the results before they’re published to ensure the process, analysis, and conclusions meet high standards.
If you’ve participated in a trial, researchers will continue to monitor your wellbeing and progress for a set period of time.
Are clinical trials safe?
All clinical trials are overseen by the FDA, which establishes and enforces standards for conduct. They must also follow federal government regulations to protect participants from unreasonable risks.
All studies also undergo an ethical review by an Institutional Review Board (IRB) or Ethics Committee to ensure the rights, safety, and wellbeing of the people involved. However, although they’re designed with safety in mind, there may be some level of risk due to the nature of the investigation.
Before you join a trial, carefully read the informed consent document which will detail the potential risks as well as your rights. Raise any questions or concerns with the research team, and consult a healthcare professional who will help you make an informed decision based on your individual circumstances.
Benefits of clinical trials
There are many benefits of getting involved in a clinical trial. By agreeing to participate, you can:
- contribute to scientific discoveries about medical interventions
test treatments or procedures that could save lives or improve patient care - access experimental treatments before they become available to the general population
- access regular medical attention from doctors and other health professionals who are part of the research team.
- play an active role in your health and try different treatments
Potential risks of clinical trials
As is the case for any drug or intervention, clinical trials involve a level of risk, and the specifics will be detailed in the informed consent document.
There could be some unpleasant side effects, and in extremely rare cases, experimental treatments can cause life-threatening complications. As such, before you agree to take part, discuss the safety considerations, risks, and benefits of a clinical trial with the research team and your healthcare professional.
How to find and participate in a clinical trial
If you're considering taking part in a study, there are several ways to find and volunteer in a clinical trial that suits your specific requirements.
- If you have an existing medical condition, speak to your doctor or support group as they might be aware of relevant studies.
- You can also try online clinical trial databases, such as ClinicalTrials.gov, which allow you to search for trials based on criteria such as medical condition or location.
- Research centers, academic medical centers, and hospitals often conduct trials, so check their websites or phone to inquire.
- Pharmaceutical companies sponsor many clinical trials, and their websites might contain information about upcoming trials and how to participate.
Conclusion
Clinical trials are a vital part of the scientific process leading to medical discoveries. Without them, life-changing drugs and treatments can’t be released to the general public. By taking part in this important research, you're helping to change lives as all research – whether successful or not – reveals valuable insights.
Always do your research before getting involved to find out how the trial could be beneficial, what’s involved, and what risks are associated with it. Make sure to take time to read and understand the informed consent document before you agree to take part, and discuss any questions or concerns with the research team and your own doctor.