Clinical Trials

Thinking about withdrawing from a trial

It is important to know that anyone can withdraw from (leave) a trial at any point, without giving a reason, and without affecting their care. Many people we talked to remembered staff making a special point of saying this, which they found reassuring. Some wanted to get this message across to other patients thinking about a trial. 

Although it was reassuring to know they could drop out, some people felt strongly they had made a personal commitment and ought not to withdraw if at all possible. This might be from a sense of responsibility to staff or a general feeling of duty, or because they worried about wasting resources or damaging the research. Comments included “I’d given my word”, “I don’t want to spoil their trial”, “Don’t do a runner”, “You didn’t want to let the side down”, and “One has to go ahead with it. One undertakes these things seriously.”

Side effects were a common reason for thinking about dropping out. It is important to report any side effects promptly, as this tells the researchers something important. They may be able to help manage the side effects, or advise you whether you should stop taking part. Withdrawing from a trial because of side effects is entirely reasonable and no-one should feel they have to stay in for the sake of the trial or that they have failed if they stop.
Harry almost gave up near the beginning of a trial of blood pressure medication because of side effects.
Sometimes people felt there were some gaps in the information they had received at the start, and they might have felt differently if they had known at the outset things they learned about later. For example, David was worried by newspaper reports of possible long-term risks from the treatment he was helping to test.
Danny had already warned staff she would drop out if she experienced side effects, as she had done in the past when taking tablets for high blood pressure. She felt staff did not react well.
Sometimes being part of a trial involves quite a time commitment, for example attending extra appointments and tests, travelling to and from hospital, taking time off work, or spending time being interviewed or completing questionnaires. (See ‘Time commitment, money and other practical issues’, and ‘Appointments, monitoring and questionnaires’). Most people did not mind this, and many felt reassured by frequent contact with staff and even enjoyed their visits. However, it could also become burdensome. The UK Clinical Research Collaboration Booklet on Understanding Clinical Trials has a checklist to help people find out what practical issues they need to consider.
Even though the trial involved injecting herself into the stomach, which was unpleasant and uncomfortable, Sarah carried on as long as she could. But eventually she gave up – the final straw was when she began to find the smell of the injections upsetting.
Several people had a preference to be allocated to one particular treatment group. (See also ‘Feelings about being allocated to a treatment group’ and ‘Feelings about being in a placebo-controlled trial’). Most people carried on even if they were disappointed at first, and looking back said they were happy with their decision to continue. However, Celia now wishes she had withdrawn when she discovered she had been allocated to the group having a longer course of radiotherapy than the standard treatment. At the time, she was mainly thinking that the standard shorter course would mean fewer trips to hospital and less inconvenience. Now she thinks the extra radiotherapy might have caused her some lasting damage.
Even so, Celia does not regret staying in the trial and hopes it might help reduce the amount of radiotherapy people are given in future.
 
A few people said they might have withdrawn after randomisation if they had been allocated to a group they did not want. (See also ‘Feelings about being allocated to a treatment group’). Rosamund wanted to be in the control group. She might have pulled out if she had been allocated to one of the groups having screening because she felt it was too invasive. Ronny would probably have dropped out if he had been allocated to a group receiving radiotherapy for prostate cancer.
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, on average, new treatments are as likely to turn out worse as they are to turn out better than existing treatments. This means that, going into a trial, everyone, regardless of the treatment group to which the computer allocates them, must have similar chances of a good outcome. If, in spite of the treatment uncertainties that the trial has been designed to address, people would strongly prefer one of the treatments being compared, they should not volunteer for the trial.

Sometimes people may be advised to stop taking part, perhaps because the side effects are too severe, especially if the treatment seems to be having no effect. (See ‘Side effects and queries’).


Anthea herself had been determined to stay in the interferon trial despite the side effects but she knew some patients had to give up. If Taxol (paclitaxel) had worked for her she would have stayed in the trial despite the side effects.

Amanda withdrew from a trial of early intervention to prevent diabetes for a very different reason. She had been through screening and fully intended to take part, until she discovered later that trial staff had been in touch with her GP without her knowledge.
It is important to note that this trial was conducted some years ago before more recent guidance was introduced, but even at the time Amanda thought it was unethical to tell her GP. The UK Clinical Research Collaboration (see Resources), points out that current ethical guidance is that if you agree to take part in a clinical trial, all your trial records and any information that is collected about you will be kept confidential, in the same way as your medical records. The researchers cannot tell anyone that you are in the trial without asking you first (See also ‘Communication between different health professionals’).

Last reviewed July 2015
Last updated July 2011

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