Clinical Trials

Deciding not to take part in a clinical trial

Everyone who is asked to take part in a trial is free to say no, and should not feel under any pressure to take part. (You are also free to leave a trial at any time and without giving a reason – see ‘Thinking about withdrawing from a trial’). We talked to several people who decided not to take part, for various reasons. These included people who had previously volunteered for other research.

In a randomised clinical trial (often called an ‘RCT’), people are allocated at random to one of the treatment comparison groups, so that each group has a similar mix of people of different ages, sex and state of health and can be compared fairly with the other groups. (See also ‘What are clinical trials’, ‘Feelings about being allocated to a treatment group’ and ‘Feelings about being in a placebo-controlled trial’).

Randomised trials are done when we don’t know which treatment is best, in other words when the relative merits and disadvantages of different treatments are uncertain. It is important to realise that in about half of trials, the new treatment will turn out to be better, but in the other half it will turn out to be worse. However, individuals may feel uncomfortable with this level of uncertainty, and with the idea of being allocated at random to one treatment or another. They may feel they are being asked to make an impossible choice without enough information. Some wanted to be guided by their doctor and preferred to trust the judgement of an expert rather than be randomised, while others wanted to make their own decision. Being asked to make such choices at a vulnerable and stressful time was hard. (See also ‘Being asked about taking part in a trial’ and ‘Information and questions’).

By contrast, Polly decided there was not enough uncertainty to justify the trial she was asked to join, even though tamoxifen was then quite a new treatment for breast cancer. If genuine uncertainty did not exist, then the trial seemed unethical to her. (See also ‘Feelings about being in a placebo-controlled trial’).

Anton was also unwilling to take part in placebo-controlled trials, and said ‘I wasn’t very keen to take the placebo, because I’m already suffering…Then I shall tell them quite up-front. “No, if you’re giving the real tablet, I will take it, but if you’re going to give me the placebo, goodbye.” I’m only volunteering because I’m suffering.’

Anton, Hazel and Polly’s experiences all show how big differences in treatment between the trial groups affected their decisions. The risk of either getting or not getting something which could make a major difference to their lives seemed too great – especially if they knew the treatments in the trial would be available for them to choose outside the trial. In cases where a new treatment is only available within a trial people may feel they have less choice. (See ‘Reasons for taking part – personal benefit’ and ‘Reasons for taking part – helping medical science and other people’). Hazel was also very concerned about the side effects of the different treatments.

Lesley also said there was something different about a trial comparing surgery with no surgery, compared to other types of intervention which were less invasive: ‘Testing some new physio afterwards, or something like that, then you think, “Well, yes, why not? I will be a trial in that.”…It’s too drastic for me to make a decision on the biggest part, but the physio bit, if you’d have said, “Well, we can do this physio, or you can do this physio, and we’ll see which is better”, I’ve got nothing to lose, have I?”

Hazel was surprised to discover how much disagreement there was among health professionals about the design of the trial and which treatments were included, which she was not told about at the time.

She noted that it was more difficult to talk to health professionals when they were in ‘researcher mode’, when she felt they may suppress their own thoughts as clinicians in order to present a ‘united front’.

Most people who had declined to take part felt their decision was respected and that there was no pressure to change their mind.

Patients should certainly not feel their care will be affected by their decision. However, sometimes people do worry about this, as Elizabeth did. She knew she wanted the standard treatment, and therefore did not think it appropriate to join the trial, but was worried about how her consultant reacted.

Although at the time Elizabeth worried that her decision might affect how she was cared for, looking back she felt it had made no difference. (See also ‘Thinking about withdrawing from a trial’).

Elizabeth explained that losing her hair would have meant a real loss of identity for her, and would have upset her family too. (See ‘Side effects and queries’). Concern about side effects often influenced people’s decision not to take part. The trial Rose was in closed early because the researchers could not find enough volunteers. The research nurse told her that most people did not want to risk the added side effects of extra chemotherapy compared to the standard treatment of radiotherapy for inoperable lung cancer.

Many people mentioned media reports of the incident in 2006 when healthy volunteers in a phase 1 trial at a commercial research unit based at Northwick Park Hospital became extremely ill. No-one we talked to said they had been directly put off taking part in a trial because of this, but several people said it had made them think more carefully and might affect future decisions. (See ‘Attitude to taking part in another trial’). They also wondered if it might be putting other people off (though in fact there is no evidence that it has).

Concern about side effects was one of several factors affecting Marie’s decision.

Of course, the reason for running a trial is precisely because there is no firm evidence yet that a new treatment is better than an existing treatment, even though there may be good reason to think it is promising and worth testing. However, patients facing serious illness may understandably be looking for something they hope will do them good. (See also ‘Reasons for taking part – personal benefit’).

We were not able to interview anyone close to death about trial decisions, but several people reflected on how this could affect people’s decision-making. People could see it might work in two different directions:

  • a terminally ill person might feel they had nothing to lose, so might as well give it a try and perhaps benefit future patients, or
  • a terminally ill person might feel they wanted to be left in peace

Lester reflected on these issues in relation to his son Ellis, who died of Creutzfeldt-Jakob Disease, and his own views now.

Since his son died, Lester has become actively involved as a lay person in clinical trials and as an advocate for more public involvement in research. Hazel has also become an activist in this field, and has co-authored the book ‘Testing Treatments’ about trials (a web resource is available at

Most of the people who had decided not to take part in a trial said they were still very supportive of medical research in general and might take part in a trial another time. Their decision was what felt right for them as an individual at the time. As Lesley put it, ‘In retrospect, yes, I can see why it has to be done and it’s probably been done all through the ages, and I’ve probably benefited from somebody else’s trials. But when it came to me, then, I never even thought like that. But I do understand the benefits, and it’s very good….But not then. Not in my backyard. And that’s awful, isn’t it? I was a NIMBY - I’m sure a lot of people are.’

The level of time commitment required to take part in a trial was not something which had deterred anyone we talked to from taking part. However, some had heard of other people who had said no for this reason, and it had caused some people to withdraw or think about it. (See ‘Thinking about withdrawing from a trial’, ‘Time commitment, money and practical issues’ and ‘Attitude to taking part in another trial’).

Last reviewed September 2018.
Last updated July 2015.


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