When you find a clinical study concerning your condition, it may seem natural to assume that you will be able to participate. However, every clinical study has specific requirements for who can take part. You may therefore be told that the study is not suitable for you, even if you have the condition being investigated.
This can feel disappointing, but it is important to understand that being ineligible is not a judgement of you as a person. It does not necessarily mean that you are too ill or not ill enough. It usually means only that you do not meet every requirement for that particular study.
What are eligibility criteria?
Before a clinical study begins, researchers prepare a detailed plan explaining how it will be conducted. This includes a description of who may participate.
These requirements are known as eligibility criteria. They are commonly divided into inclusion criteria, which are the conditions you must meet to participate, and exclusion criteria, which are circumstances that prevent participation.
The criteria vary between studies. They may relate to your age, diagnosis, stage of disease, previous treatments, other medication or general health.
Why are the criteria necessary?
One of the main purposes of eligibility criteria is to protect participants. An investigational treatment may, for example, carry particular risks for people with certain conditions, impaired organ function or other medication use.
The criteria also help researchers assess the treatment as accurately as possible. If participants have very different conditions, treatment histories and health circumstances, it can be difficult to determine whether the results are caused by the treatment under investigation or by other factors.
What factors can affect eligibility?
There are many reasons why a study may not be suitable for you. These may include:
- you are outside the age group being studied
- your condition is at a different stage or is a different subtype
- you have previously received a particular treatment
- you take medication that may interact withthe investigational treatment
- you have another condition that could increase the risks of participation
- your blood test or examination results fall outside the study limits
- the study has already recruited the required number of participants
The requirements can be highly specific. It is therefore not always possible to determine from a short study description whether you can take part. A conversation and several assessments are often needed.
How is your eligibility assessed?
Before you are formally enrolled, you will usually go through a screening period. The research team will ask about your condition, previous treatments, medication and general health.
You may also have assessments such as blood tests, blood pressure measurements, scans or a heart examination. The assessments required depend on the study.
Even when an initial conversation suggests that the study may be suitable, the screening results may show that one of the criteria has not been met.
Are the criteria the same in every study?
No. Two studies investigating the same condition may have very different requirements because they may focus on different treatments, stages of disease or patient groups.
Being unable to participate in one study does not mean that you will also be unable to participate in another. A different study may be better suited to your circumstances.
Can eligibility criteria be too restrictive?
Eligibility criteria are intended to keep studies safe and ensure that the results can be interpreted correctly. At the same time, there is growing awareness that criteria should not be more restrictive than necessary.
Very narrow criteria may mean that study participants do not reflect the patients who will eventually use the treatment. Researchers and authorities are therefore working to broaden eligibility criteria when this can be done without compromising safety.
Being ineligible is not personal
It can be frustrating to spend time attending conversations and assessments and then be told that you cannot participate. However, being ineligible does not mean that your interest or effort was wasted.
The study team may be able to explain why the study is not suitable and whether other relevant opportunities are available. You can also speak to your own doctor about other clinical studies or treatment options.
The most important consideration is that participation is safe for you and that the study can produce reliable results. Eligibility criteria help to ensure both.
If you are interested in getting involved, take a look at our current studies here.
Sources
Frequently Asked Questions | ClinicalTrials.gov
https://www.cancer.gov/research/participate/clinical-trials/how-trials-work
https://www.cancer.gov/news-events/cancer-currents-blog/2019/expanding-clinical-trial-eligibility-criteria
https://dctd.cancer.gov/research/research-areas/clinical-trials/modernization/criteria-expand-trial-eligibility
Clinical Trials Regulation | European Medicines Agency (EMA)