Clinical trials are an imperative element of medical research, and as such, certain eligibility requirements must be met before someone can participate. This eligibility criteria is responsible for maintaining the safety and scientific validity of clinical trials and their subsequent results.
Every single trial will have a different set of eligibility criteria, depending on a number of factors and what the trial is seeking to discover. Knowing whether you can participate in a particular trial will depend completely on whether you meet the eligibility requirements laid out by the researchers.
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Who should consider clinical trials and why?
With thousands of clinical trials taking place all over the world at any given time, there is ample opportunity to get involved in a clinical trial, but there are certain groups of people who may benefit most from participating.
For example, people with rare, serious, or life-threatening conditions may consider taking part in a clinical trial because none of the standard or approved treatment options have worked so far. Likewise, they may come with nasty side effects that they are no longer able to tolerate. People with very rare conditions may even find there are no treatment options available, and so the prospect of a treatment being available via clinical trial would be a welcome opportunity.
For researchers, there will be a set eligibility criteria for each trial, which will determine the types of people who should participate. However, it’s always important for clinical trial teams to ensure inclusion and diversity. People from a variety of lifestyles and diverse backgrounds should be encouraged to join clinical trials to advance health equity and gather more accurate and reliable results.
Why do people join clinical research?
There are many reasons why a person might decide to participate in clinical research, and it all comes down to the individual. However, when thinking about overarching motivators, some of the key reasons cited for joining a research trial include:
- Helping researchers and the wider medical landscape to learn about certain conditions or advancing treatments.
- Being a part of discovering health information that could help future patients and generations.
- Gaining a deeper understanding of a particular condition they are living with.
- Possibly receiving a drug or treatment that is not yet approved for wider use that could prove effective for a certain condition.
- Feeling freedom to play a more active role in their health and health outcomes.
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What are clinical trial eligibility criteria?
During the design stage of a clinical trial, researchers will establish clear guidelines that define who can and cannot participate in the study. These guidelines are known as the “eligibility criteria” and describe the characteristics that all volunteers must share.
Most eligibility criteria include details about age, gender, medical history, and current health status, but studies may also require more stringent requirements. For example, they may require participants to have received a certain vaccine as a child, lived in a certain location, or carried out a particular lifestyle habit.
Eligibility criteria differ between studies and depend on the study objective and what researchers seek to discover. They are also useful as they can help to quickly match individuals to appropriate studies without wasting the time of volunteers and researchers. This also optimizes the potential for gathering reliable and meaningful findings and ensuring the test treatments are suitable for the study group.
Why do clinical trials have eligibility criteria?
Clinical trials must have eligibility criteria in place to ensure the study group shares certain characteristics that will result in more reliable and accurate trial findings. Eligibility criteria are also important for minimizing risks and ensuring the safety of participants throughout the study.
Enrolling participants with a defined set of shared characteristics that align with the study’s goals ensures the results are due to the condition under study, and not other factors. This means the results obtained are reliable, effective, and scientifically valid. The criteria also ensure anyone who could be made unwell or have their condition made worse by taking part is not exposed to the risk of the study.
Types of clinical trial eligibility criteria
While there are several factors at play when determining eligibility criteria, there are also two different types of clinical trial eligibility criteria to understand: inclusion and exclusion criteria.
Clinical researchers often use both methods because they serve complimentary but distinct purposes in participant selection. By using both types, researchers can ensure the clinical trial environment is safe, controlled, and suitable for delivering valid and trustworthy findings while protecting participants.
Inclusion criteria
Inclusion criteria refers to the key features of a target population that researchers will use to answer the research question. These criteria are used to help identify individuals who meet specific characteristics that are essential for the study objective and typically include age, health status, or specific medical condition.
By using inclusion criteria, researchers can make sure that the trial volunteers are completely appropriate and relevant to the question the study is looking to answer. This ensures the results of the study will be applicable to the intended wider population.
Exclusion criteria
In contrast to inclusion criteria, exclusion criteria refer to the features of a target population that should be excluded from the trial. This criteria helps researchers find people who should not participate due to factors that may introduce risk or interfere with the study results.
This is important because a person may meet all the inclusion criteria, but for example, have an underlying health condition on the exclusion list. Exclusion criteria factors typically include current medications, pre-existing medical conditions, behaviors, or lifestyle factors that could negatively affect the participant’s health or trial result reliability.
Common factors that determine eligibility
To ensure participants selected for a clinical study are suitable and the results will be safe and meaningful, researchers consider several factors when establishing the eligibility criteria. Ranging from medical history and health status to age and lifestyle factors, there is a lot for researchers to consider before they can identify whether a person is an appropriate match for the study’s goal and requirements.
Medical history
In the majority of clinical trials, a person’s medical history is a key factor in determining their eligibility. This can include pre-existing conditions, previous diagnoses, test results, and more.
Researchers may exclude individuals with certain health conditions or those who have undergone certain treatments or surgery to ensure their safety, as well as study accuracy. However, there are also clinical trials that include participants based on an element of their medical history. For example, if a trial is studying a certain condition and they need participants living with that particular condition.
Current health status
A person’s current health status will also be assessed to determine whether they meet the eligibility criteria of a clinical trial. This often includes physical health assessments, laboratory tests, and imaging tests. By carrying out these evaluations, researchers can ensure the participants meet the trial’s health requirements and are physically capable of taking part without risking their well-being or the validity of the trial.
Age and gender
Many research teams will also specify a certain age group or gender in the eligibility criteria of their study. This may be to understand how a treatment affects these populations specifically, or it could be because they are studying a condition that only affects a certain age group or gender. For example, menopause-related trials would target women, prostate cancer trials would target men, and treatments for childhood illnesses would target children.
Age and gender are also important considerations when testing certain medications or interventions. This is because, even if a test is open to all ages and genders, these age and gender factors can influence how a person responds to the treatment and therefore influence the trial design.
Lifestyle factors
Certain lifestyle factors can also have an impact on a person’s eligibility for a clinical trial. These may include smoking, alcohol use, diet, and exercise frequency. Each of these habits can affect the outcomes of the study or the safety of a participant, so clinical researchers may choose to exclude individuals whose lifestyle choices could interfere with the study.
Genetics and biomarkers
The clinical trial landscape is constantly innovating, and in recent times, personalized medicine is becoming increasingly important. This means genetic factors and biomarkers may influence a person’s eligibility. For example, researchers might choose to target individuals with specific genetic markers or conditions. This can ensure the treatments being tested in the study are tailored to the most suitable participants to deliver accurate and beneficial results.
Exceptions and special cases for participating in clinical trials
While clinical trials often impose strict and rigid eligibility criteria, there are certain exceptions where those who may not qualify “on paper” can still take part. These cases typically involve compassionate use programs, special populations including children and the elderly, or trials for rare and life-threatening diseases.
Compassionate use or expanded access
Compassionate use or expanded access programs are designed to provide unapproved drugs, treatments, or therapies to people with serious or life-threatening conditions where no other treatment options are available. In essence, they are often seen as a “last resort”. Individuals may still gain access to these studies even if they don’t meet the standard eligibility criteria.
Pediatric and geriatric populations
Children and the elderly have unique health needs compared to the general population, so they are often given special consideration in clinical research. For example, pediatric clinical studies may require different dosage forms or testing for growth and development, which differ from the rigid criteria set out for the general population. Likewise, studies involving elderly participants will need to consider age-related health conditions.
Both groups of people require careful attention to safety and treatment effectiveness to ensure the populations are protected. This is why they may be granted special access to a trial, or be asked to take part in clinical trials that have been designed specifically for them.
Participation in rare disease trials
The nature of rare diseases means there are not always a vast number of clinical trials available for participation. This means participating in a clinical trial for a rare disease can be challenging, but it also poses challenges for researchers with a much smaller participant pool to choose from.
In rare disease trials, the eligibility criteria are typically more flexible to ensure participants with rare conditions can still access potentially life-saving treatments. In some cases, researchers may adjust their criteria or allow broader participation to accommodate the limited participant pool.
How to find out if you qualify for a clinical trial
Establishing your eligibility for a clinical trial is fairly straightforward thanks to the strict criteria set out by researchers of a trial. However, it does still involve a series of steps to ensure you align with the trial’s objectives and requirements.
Review the clinical trial protocol
The first step in determining whether you are eligible to participate in a trial is to thoroughly review the trial protocol. This document will highlight the inclusion and exclusion criteria, which you can use to establish whether you meet them. For example, it will tell you the age, gender, health condition, and medical history required for participants.
By understanding the trial protocol, you can better determine whether you meet the necessary requirements to participate. If you don’t, you can move on to looking at another trial that may be more suitable for you.
Discuss with your healthcare provider
If you established that you were suitable for participation in a trial after reviewing its protocol, it’s a good idea to speak with your healthcare professional before making a decision. This is especially important if you are planning to join a trial that looks at a specific medical condition, or if you have certain health conditions.
Your healthcare professional can help you understand more about the trial, including the risks and benefits of taking part, particularly concerning your unique health status. They may also provide insights into whether the trial is suitable for you based on your medical history and any current treatments.
Contact the trial’s research team
If you’re happy with the trial protocol and you’ve talked it through with your healthcare professional, the next step is to reach out to the clinical trial team. They will be on hand to provide further information about the study and its eligibility requirements, answer any questions you have, and guide you through the screening process.
Unsure about what to ask before joining a clinical trial? Check out our thorough guide for the key questions to consider, so you can make a confident and informed choice.
What happens if you don’t meet eligibility criteria?
Whether you got to the screening process and were found to be unsuitable, or you didn’t even get that far, there are still other ways to get involved in clinical research. If the protocol doesn’t suit you, you can look for alternative trials to find one more suitable. If you were deemed ineligible at screening, many clinical trials offer opportunities for potential participation in future studies, so we always recommend staying connected with the research team.
You could also sign up for patient registries to keep up to date with what’s coming up. These registries use your personal information to match you with upcoming clinical trials that may better suit your condition or health status. Be sure to always keep your information up to date on these registries just in case an opportunity comes up.
Where can I find clinical trials?
Online databases and trial registries are some of the easiest ways to find clinical trials that you may be suitable for. You can search based on several criteria, including location, medical conditions, and treatment types, and you can often find the inclusion and exclusion criteria to help you filter. This makes it easy to find what you’re looking for and exclude anything that’s not relevant to you.
You can also expand your search for a suitable clinical trial to include hospital websites, research institutions, and nonprofit organizations or local groups that focus on specific medical conditions. You may also want to speak with your healthcare provider as they will often be privy to clinical trial information that isn’t yet in the public domain, and they will also know whether it’s relevant and suitable for you.
Summary
Understanding the importance of clinical trial eligibility criteria is key to finding a clinical trial that is suitable for you. But it’s also an important feature of clinical trial design in the wider medical landscape, helping researchers ensure participant safety and improve the validity and accuracy of trial results.
If you’re keen to get involved in a clinical trial, our simple clinical trial search database can help you discover suitable trials in minutes.
FAQs
Are clinical trials safe?
There is always an element of risk in a clinical trial, but safeguards are in place to ensure clinical trial safety. For example, the FDA works hard to protect clinical trial participants by ensuring they have reliable information before they decide to take part. Additionally, the Federal government has put regulations and guidelines in place to ensure researchers protect participants from unreasonable risks.
Before joining a clinical trial, you will be asked to read and sign an informed consent document that details your rights as a participant, as well as study details including potential risks, benefits, and requirements.
Can I apply for multiple clinical trials?
It is possible to apply for multiple clinical trials at one time, but you may not be eligible to participate in more than one at a time. This could be due to overlapping treatment protocols or potential risks and again comes back down to the inclusion and exclusion eligibility criteria. Some trials may have criteria that disqualify you from the trial if you are taking part in another, so you would have to gather this information before agreeing to take part. Clinical trials can also be time-consuming, and you may not have time to participate in more than one at a time.
What happens if my health changes after being accepted?
If your health has changed before your clinical trial starts, or throughout the study, researchers may need to reassess you to ensure you are still eligible for participation. Some changes may be expected so no action will be needed. All health changes should be disclosed to the research team, no matter how big or small, or when they occur. Depending on the health change, you may be asked to withdraw from the trial to ensure your safety.
Are there costs involved in screening or participating?
For most clinical studies, study-related treatments, tests, and screenings are covered by the trial sponsor. However, you may need to pay for other trial-related expenses such as travel, accommodation, or non-study-related medical care. In some cases, these expenses are reimbursable though, so always clarify financial details with the trial organizers during the informed consent process.
Can I appeal if I’m excluded from a trial?
It is very difficult to appeal a decision if you are excluded from a clinical trial. This is because the eligibility criteria are established to ensure safety and reliability, and there would be a firm reason in line with this as to why you’ve been excluded. However, you can seek more information about the exclusion reasoning. In some cases, the trial organizer may consider an exception or recommend different trials that may be suitable for you.