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Clinical trials

Clinical Trials

A clinical trial is a research study, where a new drug or treatment is tested on people to assess its benefits and risks.

All new treatments have to go through trials to ensure they are safe and tolerable, and to test whether they are better than existing treatments.

People choose to take part in a clinical trial because they want to contribute to finding new ways of treating health problems, or because they may benefit from a new treatment themselves. There are pros and cons to being involved in a clinical trial. Think about your options carefully and discuss them with others.

What is a clinical trial?

A clinical trial is a research study, testing a new drug or treatment on people to find out about its benefits and risks.

A trial will try to find out:

  • if the treatment is safe
  • if the treatment has any side-effects
  • if the new treatment is better than any existing treatments.

Developed in partnership with NAM

  1. Background
  2. Research
  3. Joining
  4. Things to consider


People choose to take part in clinical trials because this research helps doctors understand more about a disease or condition, which may benefit them or others like them in the future.

In the UK, research and clinical trials are part of the NHS’s work. The people who do research are often the same doctors and other health professionals who provide treatment. This research will often take place in hospitals or clinics. Research also takes place in universities and research institutes, in social care services, or in the private sector (such as by a pharmaceutical company).

There are legal requirements on how a trial should be run. An organisation called the Medicines and Healthcare products Regulatory Agency (MHRA) needs to review and approve every trial, which must also be approved by local ethics committees.

There are different types of trials, depending on the research methods used, and different stages, or ‘phases’, depending how far research has got into a new treatment or drug.

All trials have what is called a protocol. This sets out the trial's aims and objectives. Trials also have rules about who can and cannot join. These are called inclusion and exclusion criteria. Often, for example, women who are pregnant or who want to become pregnant cannot join a clinical trial.

You can find more information on clinical trials, and on making the decision whether or not to join one, on the NHS Choices website and in Understanding Clinical Trials. The UK Clinical Research Collaboration can also provide you with more information about taking part in a clinical trial.


What sort of clinical trials look at HIV treatment and prevention?

Clinical trials for people with HIV currently taking place are looking at some key areas of HIV treatment and prevention:

  • Treatments to attack HIV at different stages of its lifecycle in order to stop or delay it damaging the immune system. This is how drugs in different classes of anti-HIV drugs are explored and developed.
  • Treatments for side-effects, including long-term side-effects and the impact of ageing, and the study of drug interactions.
  • Treatments for other conditions often seen in people with HIV, such as diabetes, hepatitis or tuberculosis.
  • Ways of managing treatment and healthy living.
  • Methods of preventing HIV, such as a vaccine and pre-exposure prophylaxis (PrEP).

What have we learnt from HIV clinical trials?

Major advances in HIV therapy have been made as the result of clinical trials. For example, we know more about choosing anti-HIV drugs and how and when treatment should be taken from the findings of trials:

  • HIV treatment is generally most effective if it consists of three anti-HIV drugs. Clinical trials can help guide the choice of which combination of anti-HIV drugs will work best.
  • Having a break from HIV treatment makes people more likely to become unwell, compared to people who stay on treatment all the time.
  • Zidovudine treatment during pregnancy, labour and the baby’s first weeks of life can reduce the risk of HIV transmission from mother to child by two-thirds.
  • The current recommendation that people should start HIV treatment when their CD4 cell count is around 350 is based on the results of a clinical trial. A large study (called START) is currently underway to get a more detailed understanding of the best time to start HIV treatment and will report in 2015.

Clinical trials have also shown how to best manage other conditions that are common in patients with HIV, such as hepatitis.

Research is also looking at ways of preventing sexual HIV transmission, through the use of anti-HIV drugs as pre-exposure prophylaxis (PrEP), and at a vaccine against HIV. The HPTN 052 study showed that being on effective HIV treatment makes it 96% less likely someone will pass HIV on to their sexual partner.


How can you join an HIV clinical trial?

Staff at your clinic may know about trials that are being carried out. You could ask your doctor or nurse about any research happening that might be appropriate for you to join.

There are also several registers, or lists, of trials going on at any time. You could ask at your clinic about how to find these.

UK CAB, an HIV advocacy organisation, also has information on how to find clinical trials and has listings of current trials.

If you hear of or read about a trial that interests you, the first step is to talk to the trial's contact person. They should give you some information about the trial.

The staff at the trial centre will usually ask you some questions to check that you meet the basic entry requirements for the trial, and you may have a physical examination and a blood test. After the results of all the tests are available, the trial staff will let you know whether or not you are eligible to take part.

It does not necessarily matter if you are currently receiving treatment at a different clinic or hospital to where the trial is being carried out. But you should be sure to tell your regular doctor if you do join a trial at a different centre. You may also want to discuss whether or not to join a trial with your doctor or another member of your clinic team.

How do you decide whether or not to join a trial?

New research cannot lead to reliable findings unless people agree to take part and, by joining a trial, you can contribute to important medical research. But it’s important to think carefully about joining a trial.

You can find out more about recent research into HIV prevention, treatment and care on http://www.aidsmap.com/.

You can find more information on clinical trials, and on making the decision whether or not to join one, at the NHS Choices website and in Understanding Clinical Trials, from the UK Clinical Research Network.

Things to consider

There is no right or wrong time to join a trial. People join trials at different times and for different reasons. It is something that is best decided in close consultation with your healthcare team and it is worth taking plenty of time to think carefully about your treatment options, and to ask questions, before deciding whether joining a trial is the best option for you.

Reasons to join a trial

  • You may have access to new drugs, or to new forms of treatment, which may be more effective than existing ones.
  • You will receive more frequent monitoring and have access to the most advanced tests.
  • The findings of the research may benefit other people with HIV.
  • You may receive a small payment, although this is not very common – sometimes patients receive cash compensation for participating in a study or travel expenses.

Reasons not to join a trial

  • You are concerned about being on a treatment where the outcome or effectiveness is not yet known.
  • You already know which treatment you want to take.
  • You don't want to take the chance of being given a placebo (‘dummy’ pill).
  • It would involve too many hospital or clinic appointments for you.
  • The pill-taking timetable, or restrictions on your daily life, don’t feel manageable.
  • You are worried about possible unknown side-effects.
  • You are pregnant, or want to be, or don't want to use the form of contraception required by the study.

You will also need to consider your own motivation for taking part in a trial, and what you will need to take into account.

  • Can you commit to taking the treatment as required?
  • Can you commit to attending all the appointments involved?
  • Can you meet any other requirements of the trial?
  • Do you have support from friends or family if needed?
  • Do you agree with the trial’s design and requirements?

You can find more information on clinical trials, and on making the decision whether or not to join one, at UK CAB; on the NHS Choices website; and in resources provided by the UK Clinical Research Collaboration.



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The Information Standard: Certified member

This article was last reviewed on 4/7/2014 by R. Bignami

Date due for the next review: 1/7/2016

Content Author: S. Corkery, NAM

Current Owner: Greta Hughson (NAM)

More information:

NHS Choices Clinical trials and medical research - Joining a trial 14 January 2013


National Institute for Health Research Understanding clinical trials October 2010


NHS Choices Clinical trials for HIV


UK-CAB Is a clinical trial right for me? 20 January 2011