Clinical Trials

Why people may not be eligible to join a trial

All trials have guidelines about who can take part. These are called eligibility criteria. Eligibility criteria are used to ensure that trials include the sort of people who may benefit from the treatment, and to make sure that people who take part are not exposed to avoidable risks. Inclusion criteria help the researchers to decide who can take part in the trial. Some trials only include people in a certain age group, or of one sex, or at a particular stage of their illness. The exclusion criteria state who cannot take part in the trial. For example, people who are already taking particular medicines may be excluded as these may affect the trial treatment. (See Resources for more information).

For some people, being told they do not meet the eligibility criteria can be good news for their own health.
Sarah was more disappointed to find she was not eligible for a trial because she did not meet one of the inclusion criteria. She felt this was something her doctor should have realised earlier.
Charles was also disappointed to discover he was excluded from a trial because he had turned 66 in between the first and second appointments. He felt it was an avoidable mistake and was not well handled. Not only did the researchers lose a volunteer for that study, but it has also made him a bit more reluctant to volunteer again. However, he said he did not want others to be put off by his experience.
Anton has been in several trials and is always keen to take part. He describes how he tries to convince staff to let him join, even if he is not strictly eligible.
Understandably people looking for a cure may be desperate to take part in a trial. However, it is important to remember that there may not be a trial which is suitable for you. (See also ‘Difficulties finding a trial to join’ and ‘Reasons for taking part – personal benefit’). Some exclusion criteria may be there to protect your own safety; others may help to ensure that the trial results will be easier to interpret. If you want to know why you are not eligible for a trial to which you would like to contribute, ask the researchers to explain why you should not participate.
Danny was nearly excluded from a trial after it was discovered that she would be on holiday abroad when her next appointment was due. Eventually a way round it was found, but she was annoyed that trial staff had not planned ahead to allow for summer holidays. She even wondered how valid the trial was if it only included people with nothing to do all summer.
There may be good reasons why someone should not be included in a trial, either for their own health or for the scientific validity of the trial. This should not be taken as a personal rejection. However, Danny explains that, as a former teacher in a disruptive pupil unit, she found the word ‘excluded’ problematic, and felt the way staff talked to her about this could have been more sensitive and helpful. (See also ‘Information, communication and questions’).

Last reviewed September 2018.


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