Clinical trials and research

Clinical trials and research


Research and clinical trials are an everyday part of the work done in the NHS.

The people who carry out research are mostly the same doctors and healthcare professionals who treat people. Their aim is to find better ways of looking after patients and keeping people healthy.

There are many different types of research. They cover a range of activities, from working in a scientific laboratory to carefully noting patterns of health and disease, and developing new treatments.

Health and social care research looks at many different issues, from illness, disease and disability to the way health and social care services are provided by the NHS.

Why carry out research?

People being cared for in the NHS benefit from past research, and continue to benefit from research that’s currently being carried out.

Healthcare professionals know a great deal about health, disease and treatments, but much remains uncertain. Research can find answers to things that are unknown, filling gaps in knowledge and changing the way that healthcare professionals work.

This means that treatment, care and patients’ quality of life are improved and avoidable early deaths are prevented.

Where is research carried out?

There’s a huge range of different types of research into health and disease. Much research is carried out in the NHS, but some takes place in universities and research institutes, in social care services, or in the private sector.

How is research funded?

Research that takes place in the NHS may be paid for by one of a number of different organisations, and often more than one organisation working in partnership. They include:

However the research is funded, the people who take part in it are protected in the same way. Read more about how trials are regulated.

If you’re asked to be involved in research, you should be told who is funding it. When research is published, the organisations that have funded it should be declared.

How can I get involved?

You can look for research studies yourself by asking your doctor or a patient organisation, or by looking on the internet, such as on the UK Clinical Trials Gateway.

Alternatively, if you’re being treated for a condition for which research trials are currently being conducted, you may be asked whether you’d like to take part in the research. Be cautious and don’t be afraid to ask questions. You can also find out more in our guide to taking part in research.

Types of research

Many different types of health research are going on at any one time.

Some studies may look at the effects of standard treatments, while other research may investigate whether new treatments offer any benefit, or how the NHS can best organise and provide services.

The main types of health research are explained below.

Clinical research 

Most research in the NHS involves people – often patients – and is usually referred to as “clinical research” or “medical research”.

One particular type of research, known as clinical trials, compares the effects – both wanted and unwanted – of two or more treatments.   

Observational research

Observational research uses data collected during routine clinical care to analyse:

  • the health of the population
  • the natural history of disease 
  • the safety and cost effectiveness of healthcare treatments and therapies used in daily clinical practice

Laboratory or test tube research

Before new treatments are tested in clinical trials, they’re often tested in laboratories. Only when laboratory research has shown they’re likely to work and unlikely to cause serious side effects will these treatments go on to be tested in clinical trials.

Medicines will often be tested on cells taken from living tissue that are grown and kept alive artificially (cell cultures). These cell cultures can’t survive on their own, and once the supply of nutrients, warmth and oxygen is removed, they die.

Research using cell cultures is often called test tube or “in vitro” (meaning “in glass”) research, even though a lot of laboratory equipment is now made of plastic.

Cell cultures may, for example, be used to assess the effects of possible drug treatments on cancer cells. Chemicals shown to kill cancer cells in the laboratory may be tested in further research as possible cancer drugs.


Epidemiology is a special branch of research that looks at patterns of illness and disease in groups of people. It tries to identify the causes of disease. 

Some epidemiology studies compare people who have a disease (cases) with people without the disease (controls).

Other studies look at a group of people (a cohort) over time to see what happens. Those who develop a condition and those who don’t may then be compared.

A third type of epidemiology study looks at patterns in populations, and may find associations between environmental factors, such as diet, and disease.

The main challenge faced by epidemiology is that while studies often identify strong links (associations), this doesn’t prove that one thing has caused the other. Further research is usually necessary to help decide whether this is indeed the case.

Epidemiology has nevertheless made some of the most important medical discoveries, including:

  • smoking tobacco is the main cause of lung cancer  
  • the health risks of high-fat diets and lack of physical activity

It may seem obvious now that not smoking and being active is healthy, but this wasn’t always the case.

Animal research

Research on animals is a subject of public debate and controversy, and many people have strong feelings about it.

All medicines must, by law, be tested on animals before being given to humans in clinical trials.

There are regulations to ensure animal research is only carried out when there’s no alternative, and it’s carried out humanely and is likely to bring real benefits in terms of useful knowledge.

The GOV.UK website has more information about research and testing using animals.

How research addresses what we don’t know

There are many questions about health, illness and the effects of treatment that we currently don’t have clear answers for. Knowing what the questions are makes it easier to say what future research studies should look at.

For example, there’s no medical consensus about the best treatment for an enlarged prostate gland in men (also known as benign prostatic hyperplasia, or BPH). The enlargement causes urinary problems.

BPH can be treated with lifestyle changes, medicines or surgery, or by simply keeping an eye on things (known as watchful waiting). There’s no convincing evidence that one type of treatment is better than the other, and it may be a matter of personal choice by the doctor or patient, depending on what symptoms the condition causes.

Research is important to try to understand which treatment may work best, and when.

The right research project

There’s benefit in repeating research if uncertainties remain. However, if the answer is already known, it will be more important to move on and ask another research question.

Doctors and researchers – and, increasingly, patients and the public – review research that’s been carried out and try to choose research projects that look at important unanswered questions.

Research ethics committees now ask researchers and others seeking approval for new trials to show that they have already reviewed previous research systematically (systematic reviews). Without doing this, and consulting patients and other users of research, researchers are less likely to address questions that are relevant to patients.

Collecting together what is unknown

For centuries, researchers and scientists have made huge efforts to collect together what they know in medical libraries and, more recently, in electronic databases.

Now, researchers are collecting what they’re not sure about in the UK Database of Uncertainties about the Effects of Treatments (UK DUETs).

The main aim of DUETs is to help people decide which of the unanswered questions are most important, such as how prostate cancer should be managed.

DUETs identifies the need for future research using guidelines from the National Institute for Health and Care Excellence (NICE) and other publications that highlight gaps in our knowledge.

Researchers also have increasing interest in the questions that matter to people who are ill, their families, and those who care for them. The James Lind Alliance helps patients and medical professionals decide which uncertainties should be prioritised for further research.

Managing prostate cancer

There are uncertainties about whether it’s a good idea to diagnose prostate cancer early. This is because the disease is often so slow-moving that it doesn’t become a life-threatening condition.

There are also uncertainties about how best to investigate men who may have prostate cancer and how to treat them. Only good research can address and reduce these uncertainties.

Read more about prostate cancer screening.

What are clinical trials?

A clinical trial is a type of clinical research that compares one treatment with another. It may involve patients or healthy people, or both.

Small studies produce less reliable results than large ones, so studies often have to be carried out on a large number of people before the results are considered sufficiently reliable.

Why clinical trials are important

Doctors and other healthcare professionals and patients need evidence from clinical trials to know which treatments work best. Without this evidence, there’s a risk that people could be given treatments that have no advantage, waste NHS resources, and might even be harmful.

Clinical trials help to find out if:

  • treatments are safe 
  • treatments have any side effects 
  • new treatments are better than the standard available treatments

Many NHS treatments have been tested in clinical trials. But the evidence for some treatments is incomplete. Read more about what we don’t know

The NHS aims to inform patients about research relevant to them and offer more patients the opportunity to take part in clinical trials if they want to.

What clinical trials can find out

Clinical trials can help:

  • prevent illnesses by testing a vaccine 
  • detect or diagnose illnesses by testing a scan or blood test 
  • treat illnesses by testing new or existing medicines 
  • find out how best to provide psychological support  
  • find out how people can control their symptoms or improve their quality of life – for example, by testing how a particular diet affects a condition

Trials follow a set of rules, known as a protocol, to ensure they’re well designed and as safe as possible, they measure the right things in the right way, and the results are meaningful. A full protocol should be available to anyone who’s considering taking part in a trial and wants to see it.

Many clinical trials are designed to show whether new medicines work as expected. These results are sent to the Medicines and Healthcare Products Regulatory Agency (MHRA). The MHRA then decides whether to allow the company making the medicine to market it for a particular use.

Read more about safety and regulation.

Entering a trial

If you’re receiving treatment for a medical condition, you may be asked if you would like to be part of a trial. You might be interested in finding out about trials taking place so you can volunteer to join one.

Read more about taking part in clinical trials, including how to join a trial.

Different stages of trials

All clinical trials of new medicines go through a series of phases to test whether the medicines are safe and whether they work.

The medicines will usually be tested against another treatment called a control. This will either be a substance containing no active treatment (a placebo) or a standard treatment that’s already in use.

Early research may involve volunteers (who may or may not have a health problem) attending a clinic to assess the effects and safety of a new treatment. Students are often thought of as the typical participants in this type of research, but in fact all kinds of people do it.

You may see advertisements looking for volunteers in newspapers. There may be a payment for this kind of research, and usually your expenses will be paid.

From these beginnings, clinical trials become larger and more complicated as the tests of safety and effectiveness become more strictly regulated. 

Phase one trials

Phase one trials aim to test the safety of a new medicine. A small number of people, who may be healthy volunteers, are given the medicine. Researchers test for side effects and calculate what the right dose might be to use in treatment (known as dose-ranging studies).

This will usually be the first time the medicine has been tried on humans, so there’s an unavoidable element of risk. To minimise the risk, researchers start with small doses and only increase the dose if the volunteers don’t experience any side effects, or if they only experience minor side effects.

Phase two trials

Phase two trials test the new medicine on a larger group of people who are ill. This is to get a better idea of its effects in the short term.

Phase three trials

Phase three trials are only for medicines that have already passed phases one and two.

They test medicines in larger groups of people who are ill, and compare new medicine against an existing treatment or a placebo to see if it’s better in practice and if it has important side effects.

Phase three trials often last a year or more and involve several thousand patients.

Phase four trials

Phase four trials take place once new medicines have passed all the previous stages and have been given marketing licences. A marketing licence means the medicine can be made available on prescription. Read more about the licensing of medicines.

In phase four trials, the safety, side effects and effectiveness of the medicine continue to be studied while it’s being used in practice. Phase four trials are not required for every medicine. 

Similar trials are used to assess the effects – both wanted and unwanted – of other kinds of treatment, including physical therapies, surgery, psychological therapies, and ways of organising care.

More information

The website of the Association of the British Pharmaceutical Industry (ABPI) has more information about the development of medicines.

About fair tests

Not only do unproven treatments need to be tested, but the tests also need to be fair.

Without a fair test, the findings from any research may not mean very much.

Even worse, an unfair test could give healthcare professionals and patients the wrong idea, and people may be given a treatment that doesn’t work or is actually harmful. They may also not be given a treatment that could be helpful.

This page explains:

Making comparisons

If someone who’s ill takes a treatment and then gets better, it could be the result of a natural recovery that would have happened anyway.

To tell if the treatment has worked, it needs to be compared with another treatment or a placebo. The two results have to be different enough to indicate a difference hasn’t occurred by chance.

Comparing a treatment with a placebo

The treatment may be compared with a placebo (a dummy treatment), such as a sugar pill, that looks the same as the treatment.

If there are fewer symptoms or other problems after a treatment than after taking a placebo, this suggests the treatment works.

Comparing a treatment with a standard treatment

Where a treatment is already known to be effective from previous research, it’s usually not considered right (ethical) to compare the new treatment with a placebo. The new treatment usually needs to be compared with a standard treatment that’s already known to be helpful.

This makes it possible to assess whether the new treatment works better than the treatment already being used. New treatments are as likely to be worse as they are to be better than existing treatments.

Placebo effect

The placebo effect is the phenomenon of someone’s symptoms improving when they’ve only been given a dummy treatment, or even after they’ve just seen a doctor.

Sometimes a doctor’s or other healthcare professional’s reassurance, and their confident way of communicating with people who are feeling ill, helps some people feel better. The placebo effect is a largely mysterious and fascinating effect that can be quite powerful.

If you think and believe you’re going to get better, you’re much more likely to. However, this doesn’t work in all situations and for all conditions.

Dummy treatments may be given to people in clinical trials. A placebo medicine looks the same as the medicine being studied, so you don’t know which one you’re taking. Some people may feel better after taking the placebo medicine because they think they’re being given real medication. This is the placebo effect.

Placebos are particularly powerful in conditions where symptoms are important. For example, people feel pain differently and respond better to treatments they think are going to work. In extreme circumstances, some people who are in severe pain respond to a placebo as well as they would to a powerful painkiller.

But placebos don’t work for all conditions. High blood pressure (hypertension) can be lowered by active medicines, but placebos have no detectable effect. Similarly, placebo treatments don’t lower blood cholesterol, but statin medicines do.

Sham treatments that work

Researchers have designed ways of creating placebos for complementary medicine treatments, such as acupuncture.

It’s possible to carry out sham acupuncture where needles are inserted to a different depth and in different places from those used in real Chinese acupuncture. In recent trials, both types of acupuncture appeared to be better than doing nothing.

Studies have also carried out placebo surgery on people with knee pain, and these have shown the placebo surgery often has good results.

Examples of the placebo effect include:

  • four placebo tablets work better than two in gastric ulcers
  • pink dummy pills are better at maintaining concentration than blue ones
  • placebo injections are more effective than placebo pills
  • painkillers work better if they’re believed to be costly than if they’re believed to be cheap

(Source: Bad Science, Ben Goldacre, Fourth Estate, 2008)

Control groups

Participants in a clinical trial will usually be put into one of two groups. They may be put in a group where they’re given: 

  • the unevaluated treatment being assessed 
  • an existing standard treatment, or a placebo if no proven standard treatment exists (known as the control group)

The aim is to compare what happens in these groups. Participants are randomly assigned to one of these groups.

While the treatments are different in the two groups, researchers try to keep as many of the other conditions the same as possible. For example, both groups should have people of a similar age, with a similar proportion of men and women, who are in similar overall health.


The best way to get similar groups is to allocate individuals to one of the groups in the trial in an unpredictable, random way. This increases the likelihood that the two groups will be similar. This process is called random allocation or randomisation.

In most trials, a computer will be used to decide which group each patient will be allocated to. This allocation will be concealed until after each eligible patient has been accepted for the trial.

These precautions mean the people who decide whether a patient is eligible to participate in the trial can’t influence which treatment a patient is allocated to receive. This protects the study from conscious or unconscious bias, which would make the test unreliable.


Many trials are set up so nobody knows who’s been allocated to receive which treatment. This is known as blinding, and it helps reduce the effects of bias when comparing the outcomes of the treatments.

Many people feel better if they think they’re getting a better new treatment, even if the treatment is ineffective and their underlying health problem hasn’t really changed at all.

When both the medical staff organising treatment and those taking part in the trial don’t know who’s receiving which treatment, it’s called a double-blind trial.

Blinding is easier when testing medicines, but more difficult when testing other types of treatments or methods of caring for people. For example, it may be impossible to blind a trial comparing two types of surgery.

Why blinding is important

Some clinical trials measure hard outcomes such as survival, so outcome measurement is unlikely to be biased.

However, most trials measure outcomes that are more open to biased assessment. For example, patients and researchers may have to make some sort of judgement about how bad symptoms are.

If either researchers or participants know – or think they know – who is receiving which treatment (including placebos), that knowledge may influence what they report.

Participants who think they’re taking an active treatment may not want to let down the researcher, and may exaggerate benefits and minimise side effects. Researchers also may allow their hopes about a new treatment to unconsciously influence their recording of symptoms.

The result of these biases is often to overestimate how effective a treatment is. To reduce these possible sources of bias, many trials are double-blind.

Size of trials

For a trial to be a fair test, the number of people taking part needs to be large enough. For example, in a small trial of 20 people, with 10 people taking each treatment, seven people may improve on the new treatment and five on the standard treatment.

Most of us would not think of that as a fair test because, while the new treatment may be better, the finding could easily have occurred by chance.

If the trial was bigger, with 700 out of 1,000 people improving on the new treatment and 500 out of 1,000 on the standard treatment, the result means researchers can be very confident that the new treatment was better.

The degree of this confidence in the difference can be estimated. Researchers can provide ranges called confidence intervals to show you how certain their results are.

Researchers can also test how “statistically significant” a result is. This can help to show where differences between treatments are unlikely to be the result of chance.

More information

Read more about fair tests on the Testing Treatments interactive (TTi) and the James Lind Library websites, where you can also download books for free, including how to make smart health choices and understanding health statistics.

Getting involved in health research

Research isn’t just for researchers. Patients and the public can be involved, too. New research can’t lead to reliable findings unless the right patients agree to take part.

Clinical trials

Clinical trials are a type of health research that compare one treatment with another.

If you take part in a clinical trial, you may be one of the first people to benefit from a new treatment. However, it may turn out to be no better, or worse, than the standard treatment.

Read more about joining a trial.

Other health research

The public can also get involved in other types of health research. For some types of research, people are asked whether researchers may use personal information, in confidence, from their health records.

For other types of research, it isn’t necessary for the researchers to know who the participants are, and they use data from patient information that’s been made anonymous.

An organisation called INVOLVE suggests ways people can contribute to research without taking part in a trial. When the public is involved in the way research is commissioned and managed, it’s more likely to produce results that can improve health and social care practice.

The James Lind Alliance

The James Lind Alliance is an organisation that aims to identify and prioritise unanswered questions that patients and clinicians agree are most important.

This helps ensure that those who fund health research are aware of what matters to patients and clinicians.

Joining a clinical trial

If you take part in a clinical trial, you may be one of the first people to benefit from a new treatment. However, it may turn out to be no better, or to be worse, than the standard treatment.

This page explains:

Many people choose to take part in clinical trials because it helps increase understanding of how to treat a particular disease or condition. This may benefit them, or others like them, in the future.

Finding out about clinical trials 

If you’re ill and interested in taking part in a clinical trial, your doctor or other healthcare professionals may know of research being carried out that may be right for you. However, few healthcare professionals know of all the trials being carried out in their clinical area. There could be dozens, or even hundreds.

Searching the registers

You can look for information on the registers of clinical trials, such as the World Health Organization’s International Clinical Trials Registry Platform (ICTRP). This collects information from different registers to provide a central database of clinical trials.

Many of the topics in the Health A-Z have a page that allows you to search for WHO-registered clinical trials for that particular condition or treatment. You can also search for clinical trials from these topics.

None of the registers covers all the trials currently being carried out in the UK. However, the UK Clinical Trials Gateway provides information about clinical trials in the UK from several different registers.  

You’ll probably need to talk to your doctor or specialist nurse about any information on trials you’ve found in the registers.  


For some conditions, you can find out about trials from patient organisations. For example, Cancer Research UK has clear information on nearly all the cancer clinical trials happening in the UK.

Other health charities also have user-friendly information about some clinical trials. Charities that aren’t listed may not formally publish lists of clinical trials, but may know of some that are relevant to patients with particular conditions.

User-friendly clinical trials information includes:

Questions to ask

When you express interest in a trial, a doctor or nurse is likely to tell you something about it in person. You’ll also be given some printed information to take away. You may come back with some questions you feel haven’t been answered.

The UK Clinical Research Collaboration is a partnership of organisations that are establishing the UK as a world leader in clinical research. It suggests a number of general and practical questions you may want to ask.

General questions

  • What is the aim of the trial and how will it help people?
  • Has existing evidence been reviewed systematically?
  • Who is funding the trial?
  • What treatment will I get if I do not take part in the trial?
  • How long is the trial expected to last, and how long will I have to take part?
  • How long will it be before the results of the trial are known?
  • Is there an explicit commitment to report the results of the trial? 
  • What will happen if I stop the trial treatment or leave the trial before it ends?

Practical questions

  • How much of my time will be needed?
  • What extra tests or appointments will I have?
  • Will I need to take time off work?
  • Will I need extra help from family or friends?
  • Will the costs of my travel to take part in the trial be covered?
  • If the trial is testing a new drug, will I have to collect it from the hospital, will it be sent to me by post, or will I get it through my doctor?
  • Will I have to complete questionnaires or keep a diary?
  • What are the possible side effects of my treatment?
  • How could the treatments affect me physically and emotionally?
  • Who can I contact if I have a problem?
  • Will someone be available 24 hours a day?
  • How do I find out the results of the trial?

Advantages of being in a clinical trial

The main reason for carrying out trials is to assess whether one treatment is better than another.

During the trial, your treatment and progress may be monitored more closely than if you were receiving the usual treatment.

After the trial has finished, healthcare professionals will be better able to offer you the most appropriate and effective treatment for you.

Trials are very important in helping find better treatments. By being involved in a trial, you’ll obtain information and evidence that may be helpful to you in the future, as well as helping the NHS provide people with the best possible standard of care.  

Disadvantages of being in a clinical trial

The disadvantages of being in a trial are:

  • As with any treatment, you can’t be sure of the outcome. 
  • You may be given a new treatment that turns out not to be as effective as the standard treatment.
  • It’s possible you’ll experience unexpected side effects.
  • You may have to visit your place of treatment more often, or have more tests, treatments or monitoring than you would if you were receiving the standard treatment in usual care. 

Giving consent

If you’re asked to take part in a trial, you’re free to say yes or no. For people under the age of 18, a parent or guardian has to give permission. The doctor organising your treatment will usually talk to you about being involved. They should explain the possible risks and benefits.

Make sure you’re happy with the trial and have been given all the information you want before you give your consent (permission). This may mean taking some time to think about it and talk it over with family or friends, unless a decision is needed urgently because of your medical condition.

If you decide to take part, you’ll be asked to sign a form to say you’re agreeing to take part in a trial and have understood what it involves. This is called giving your informed consent.

Why you might not be able to take part

Sometimes it may not possible for you to be involved in a particular trial. For example:

  • Your condition may need to be at a particular stage.
  • You may not be allowed to receive another treatment at the same time. 
  • Some trials seek people with certain illnesses and conditions, while others need healthy people. 
  • Some trials need people of a certain age.
  • There may already be enough people in a particular category who have joined the trial.

Medical tests

Before you join a trial, you may need to have tests to see if you can take part. For example, you may have to be tested to see if you have raised levels of a particular hormone.

This will give the researchers more information about your health before you start treatment, which will allow them to tell whether there’s been an improvement at the end of the trial.

During the trial, you may have more tests to see whether the treatment is working. It may be possible for the tests to be carried out as part of your routine care, or you may have to make more visits than usual to your GP or hospital clinic.

Leaving a trial

You may decide to stop taking part in a trial if your condition is getting worse or if you feel the treatment isn’t helping you. You can also choose to leave at any point without giving a reason and without it affecting the care you receive.

If there are signs that the treatment in a trial could be unsafe, the research team or the regulators will stop the trial. Read more about how trials are regulated.

Finding out about the results

There may be a delay before the results of a clinical trial are known, particularly with larger trials, which can involve thousands of people and may take place over several years.

Even when the results have been collected and analysed, there’s a further period – usually several months – when the research is looked at and commented on by other scientists to check its quality. This is called peer review.

At the end of the trial, the researchers should make the results available to anyone who took part and who said they want to know the results. If the researchers don’t offer you the results and you want to know, ask for them.

All the main public funders of health research and the larger medical research charities require researchers to place a copy of their research on Europe PubMed Central when it’s published.

Licensing a treatment

If research has identified a new medicine, the Medicines and Healthcare Products Regulatory Agency (MHRA) must license it before it can be marketed. Licensing shows a treatment has met certain standards of safety and effectiveness.

Safety must be monitored carefully over the first few years of a newly licensed treatment. This is because rare side effects that weren’t obvious in clinical trials may show up for the first time.

In England and Wales, the National Institute for Health and Care Excellence (NICE) decides whether the NHS should provide treatments.

Why all research should be registered

Some studies are never published because they have disappointing or negative results.

The researchers might find, for example, that a potential new treatment or intervention appears to be no better than a placebo dummy pill.

Other reasons why research may not be published include:

  • The researchers may not finish writing a report because they move on to something new.
  • The researchers may not ask a journal to publish their findings.
  • The researchers may find what they’ve written is turned down by the editors of a journal.

Not being published is more than a matter of disappointment for researchers. If trials aren’t published, there’s a risk of other researchers attempting something similar again, with similar results, wasting time and resources.

There’s also a danger that while one or more disappointing studies may remain unpublished and invisible, a single positive study will be published that may attract widespread attention.

The publication of the single study may result in the wrong belief that a treatment or intervention is more effective than it really is. The treatment may even be useless or harmful.

Well-designed studies should be published whatever the results because, disappointing or not, they add to the overall understanding of health and disease.

To reduce the risk of the results of studies never being published and remaining hidden, most clinical trials now have to be registered when they begin.

Trial registers, which contain a small amount of information about a trial, reduce the likelihood that trials will be forgotten about, and that unexpected or unwanted results will be overlooked.

On the register

More and more trials are now formally registered. This means some details are recorded, usually on a publicly accessible website, before they’re started. The World Health Organization (WHO) has established what details should be recorded when a trial is registered.

Most clinical trials publicly funded in the UK – for example, by the National Institute for Health Research (NIHR) and the Medical Research Council (MRC) – have to be registered before they start to recruit people to take part in them. Since 2013, the registration of a clinical trial is a precondition for a favourable ethics opinion.

Many of the most important medical research journals, such as the British Medical Journal (BMJ) and The Lancet, won’t publish reports of clinical trials that haven’t first been registered. This means that research, whether formally published or not, can be identified by those collecting evidence or planning similar research.

What’s on the register?

According to WHO, you should be able to find out the following information about any trial:

  • the title of the trial
  • the condition being studied
  • which treatment is being compared with which
  • who can and can’t take part in the trial
  • whether people are currently being asked to join the trial
  • what the researchers are measuring to compare the effects of the treatments
  • the type of study
  • contact details for enquiries
  • who manages or funds the study
  • the number of people joining the trial
  • the date the trial was registered
  • the identifying number for the trial
  • where the trial is happening
  • when the first person joins the trial

Systematic reviews and meta-analyses

On its own, a single piece of research can be misleading. Separate, but similar, small studies can produce apparently conflicting results, often as the result of chance.

Collecting information from different trials in an organised way is a good method of showing what the overall evidence is. By using a careful “study of studies”, called a systematic review, it’s possible to distinguish the effects of treatment from the effects of chance.

For example, the first trial to show the benefits of a short course of steroid injections given to pregnant women at risk of having a premature birth was carried out in 1972. A number of later trials had results that weren’t quite so positive.

Only in 1989 was a “study of studies” of all the trials carried out. It found babies born to mothers who took steroids were much less likely to die than those whose mothers didn’t take steroids.

It wasn’t new research that made the difference in this case, but collecting together results from all the existing research.

What are systematic reviews?

Systematic reviews are now an established part of research. They look at all the studies on a topic, not just selected studies that may have a particular point of view and could result in biased conclusions.

For example, contributors to the Cochrane Collaboration, the Centre for Reviews and Dissemination, and the Health Technology Assessment Programme review all the reliable research about preventing and treating specific health problems, and publish it to help patients and clinicians make choices about healthcare.

Systematic reviews often combine findings from separate but similar studies and calculate an overall result. This process is called meta-analysis.

Systematic reviews and meta-analyses are now an important part of health research because they can identify findings that might otherwise be missed in individual studies.

Research should take place only when a systematic review of previous research has been carried out and the need for new research has been established.

Read more about systematic reviews on the Testing Treatments interactive (TTi) and the James Lind Library websites.

How trials are regulated

People running clinical trials have legal obligations that are set out in Medicines for Human Use (Clinical Trials) Regulations 2004.

Conditions include:

  • Anyone taking part in a trial must have a full understanding of the objectives of the research, and any risks and potential inconveniences they may experience when taking part. This information will be given to them at a meeting with a member of the research team.
  • A point of contact must be provided so patients can obtain more information about the trial.

Before a clinical trial of a new medicine can begin, all of the following needs to be in place:

  • The science the research is based on must be reviewed by experts. 
  • The researchers must secure funding.
  • An organisation, such as a hospital or research institute, must agree to provide a home base for the trial.
  • The Medicines and Healthcare Products Regulatory Agency (MHRA) needs to review and approve trials of a medicine and issue a clinical trial authorisation (CTA).
  • A recognised ethics committee must review the trial and allow it to proceed. 

The MHRA inspects sites where trials take place to make sure they’re conducted in line with good clinical practice (an international quality standard).

Industry trials

All trials are regulated, whether or not they take place within the NHS. The Association of the British Pharmaceutical Industry (ABPI) has issued revised guidelines on phase one trials.

Read more about the phases of trials.

Trials of other treatments

The Department of Health’s Research governance framework for health and social care describes how researchers and others are expected to work within a framework of ethical and scientific standards. This applies to all health and social research. It includes:

  • promoting good practice
  • reducing adverse incidents and ensuring lessons are learned
  • preventing poor performance and misconduct

Ethics committees

Every clinical trial is covered by regulations that protect the health, safety and dignity of the people taking part.

Research ethics committees

All medical research involving people in the UK, whether in the NHS or the private sector, has to be approved by an independent research ethics committee. The committee protects the rights and interests of the people who will be in the trial.

The committees are often based at local hospitals and are formed of local people, such as healthcare professionals, patients, lawyers and members of the public. They have to include members who aren’t healthcare professionals.

Submitting a protocol

Before they start a trial, researchers have to submit a detailed plan of their proposed research (protocol) to a recognised research ethics committee. They may also need approval from other regulators.

All clinical trials of medicines need to be authorised by the Medicines and Healthcare Products Regulatory Agency (MHRA), as do studies on medical devices.

An online system called the Integrated Research Application System (IRAS) allows researchers to use a single set of information to apply to the research ethics committee and other regulators.

Patient information

Researchers have to prepare an information leaflet about their trials for patients. The research ethics committee checks this is clear and accurate.

All those who take part in the trial are given the leaflet, with an opportunity to take it away and discuss it with friends and relatives.

The leaflet has to be in plain language, avoiding technical medical words. It has to make clear:

  • the research questions the trial is trying to answer
  • who can and can’t take part in the trial
  • how those taking part in the trial will be treated and what they’ll need to do
  • what treatment or other intervention is being used
  • what type of research it is
  • what the possible risks are to participants
  • what the possible benefits are to participants
  • who is carrying out the trial and who is funding it 
  • who participants should talk to if they have further questions

Until a research ethics committee approves a clinical trial, researchers can’t ask any participants to join it.

The committees are independent both of the researchers whose work they are reviewing and those who pay for the research.

The ethics committees that review clinical trials in the NHS are part of the Health Research Authority’s National Research Ethics Service (NRES). NRES publishes plain-language summaries of clinical trials that can be understood by anyone.

Regulating animal research

There are extensive regulations to ensure the welfare of animals in research.

These include regular inspections from government officials, and a requirement for researchers to explain their research ideas and pass an approval process before they start.

The GOV.UK website has more information about research and testing using animals.

Data monitoring committees

Some longer clinical trials that produce a lot of information over several years have early warning systems.

These help identify whether the benefits of a treatment or intervention are so good, or the potential risks so high, that the trial should be stopped early.

In a large trial that lasts several years, a data monitoring committee, which is independent of the running of the trial, will look at the information being produced by the trial earlier than the researchers.

The committee members look at results at fixed intervals, or when a reason for investigation emerges in between these intervals.

Trials should be stopped if it becomes obvious that one of the treatments being compared is clearly better or worse than the other.

However, if things are going as expected with no completely clear signals that one treatment is better, the committees will recommend the researchers carry on as intended.

Whether it’s always a good idea to stop a clinical trial early is a controversial issue. Read more about Are drugs trials stopped too early?

When things go wrong

Medical research and clinical trials are carried out by healthcare professionals whose training and everyday work is focused on the care of patients.

This work is regulated by laws and codes of conduct, and approved by local research ethics committees, whose purpose is to protect the interests of people taking part in the research.

Generally, clinical trials are safe, but sometimes things can go wrong.

The TGN1412 trial at Northwick Park

In March 2006, six men had severe and life-threatening reactions during a clinical trial. They were in a private research unit in northwest London involved in a trial for an experimental treatment that might have been developed to treat leukaemia or rheumatoid arthritis.

The trial was the first time the treatment, called TGN1412, had been used in people (a “first-in-man” trial). All previous research on TGN1412 had been in animals.

The men had serious symptoms, including vital organ failure, fever, and low blood pressure (hypotension). They had to be treated in the intensive care unit at the NHS Northwick Park Hospital in Middlesex. The men survived, but their health was permanently compromised.

A detailed investigation into what went wrong recommended many changes to the way first-in-man trials are carried out. Those recommendations have now been put in place.

What happened to the six men in the trial was widely reported in the media. It was shocking, but highly unusual. Nothing of the same scale has been reported before or since in the UK. 

All first-in-man studies are now carried out much more cautiously, particularly those that use new types of treatment with possibly unpredictable side effects.

With research carried out in the NHS, researchers are likely to have a good idea of the possible benefits and side effects of treatment. Researchers have to make the medical background clear and describe details of any new treatments or other interventions being carried out.

Read more about the expert report on first-in-man trials.



‘The nurse made sure I understood the risks’

When Kathleen Pemberton developed rheumatoid arthritis, it progressed rapidly. Within six months she was in serious pain. Most of her joints were inflamed and she had difficulty moving around.

At her first consultation at Whipps Cross Hospital in Leytonstone, east London, the specialist suggested she consider taking part in a new clinical trial.

”It was a trial of a new treatment that had been accepted for use in America, but needed to be tested in England,” says Kathleen.

”I was keen to take part because the painkillers I was on weren’t working and I was looking for a treatment that did work. I didn’t get paid any money, but I wanted to see if it could help.

”I saw a clinical trial nurse and she was thorough and helpful. She made sure I understood the risks. There was a series of consultations at the hospital, but not too many.”

While Kathleen received the medication through a drip into her arm, she was in a pleasant ward with plenty of cups of tea. She was given one of a group of medicines called TNF inhibitors, originally developed through NHS research at the Kennedy Institute in London.

Kathleen’s condition improved, and when the trial finished two years later she went on to another TNF inhibitor medicine that had already been approved for health service use.

Kathleen says that, looking back, she would take part in a trial again. ”Everybody was so kind and nice. I would recommend it to anybody. You’re well looked after.”

It was a bonus for Kathleen to know she was a small part of the research that established TNF inhibitors as an important part of rheumatoid arthritis treatment.

”The pain and mobility problems of rheumatoid arthritis are beyond belief. You’re in pain all the time.

”I’m pleased to have been one of the people who’ve shown how these treatments can help people with rheumatoid arthritis.”

‘I’m here because of women who took part in research’

Christine Gratus discovered she had breast cancer after attending routine NHS screening.

She says she’s one of many people who are grateful to women who had taken part in previous research. 

”I’m here because of all the research that was done before I found out I had breast cancer,” she says.

”I’m here with perfectly formed breasts thanks to women who took part in research that discovered that a lumpectomy (surgery to remove a small piece of breast tissue) is just as effective as a full mastectomy (removing the entire breast).

”I’m also here because of the women before me who took part in research on radiotherapy, surgery, and chemotherapy.”

In turn, she also took part in research. ”We have responsibilities as well as rights in this area. If we want treatment for breast cancer and other conditions to improve further, we have a responsibility to the women who come after us.

”People rightly make a fuss about getting the most effective treatments. But a lot of the time we don’t really know what the best treatments are, and without more research we never will.”

Christine took part in a trial to see whether it was better to let fluid drain away from the site of surgery or to use a pump, and in another trial that looked at how radiotherapy could best be targeted and at what doses.

She acknowledges the main reason she took part in the research was because she thought she would receive the best possible level of care.

”When I was diagnosed, I read about breast cancer and found that I was likely to get the best standard of care, whichever arm of the trial I was in.

”I’m really pleased that I may have helped some of the women who are being diagnosed with breast cancer now.”

‘I thought it might help me or someone else’

When Nigel Lewis-Baker was told he had advanced prostate cancer, it was too late for surgery or radiotherapy as he had probably had a fast-growing form of the disease for several years.

The only choice was one of two types of hormonal treatment. This worked for a while, but the cancer returned and he stopped taking the hormone treatment.

Nigel was then asked if he would like to take part in a trial for a new type of vaccine to treat prostate cancer. After careful consideration, he agreed. ”I thought it might help me, or it might help someone else,” he says.

He never knew whether he was on active treatment or dummy placebo injections. But he says, ”I hope it was the placebo, because whatever it was, it didn’t work for me. My PSA levels (which act as a marker for cancer growth in prostate cancer) started to climb again.”

Nigel was then switched to two types of hormone and the growth of his cancer slowed down again.

He has no regrets about being in the trial. ”I was glad I did it, even though it didn’t seem to have helped me personally. I hope the findings will benefit other men. I would certainly not hesitate to do it again.”

‘I want people to find better medicines’

Georgia Semple, who had leukaemia, has been involved with the Young Person’s Advisory Group panel that works with the Children Specialty of the National Institute for Health Research.

”Having leukaemia was horrid for me and my family,” she says. “I felt sick and tired all the time. The medicines were horrible and they made my hair fall out, and that made me cry.

”I had to go to hospital every time I had an infection, even for something small. I was on medicine for two-and-a-half years. I feel OK now, but I still get tired.
”The Children Specialty asked my daddy if I would be interested in being in its children’s group, called Stand Up, Speak Up! I said yes because I want people to find better medicines than the ones I had.

”We meet once every two months. There are about 14 children in the group and we’re split into two age groups: 9 to 12 and 13 to 18.

”We’ve learnt how medicines work, where they come from, and how trials are done. I know what a randomised controlled trial is. I’m in one for leukaemia treatment.

”We helped to make the information sheets for children better. We designed our own logos. I designed the smiley faces logo for Stand Up, Speak Up!

”Our group is helping researchers decide which trials should be done. We choose ones that should make a difference to treatments for children.”

Georgia Semple is on the Young Person’s Advisory Group panel that works with the Children Specialty to encourage young people receiving medical care to take part in research.

‘I can control my Parkinson’s thanks to animal research’

Mike Robins has directly benefited from animal research. He has Parkinson’s disease, and the severity of his tremor meant he couldn’t sit in the same room as his family and read a newspaper.

His violent shaking made such a disturbing distraction that they would take themselves somewhere else.

”It’s very difficult for a person without a tremor to understand,” he says. ”You can’t do much for yourself if you’re shaking uncontrollably, and you certainly can’t hold a proper conversation because you’re concentrating on trying not to shake.”

When he got the opportunity to have what was still experimental surgery, Mike jumped at the chance. ”I think I was the third person in this country to have the surgery, but my tremor had become so debilitating that I had to do something,” he says.

Now Mike can control his symptoms at the flick of a switch. He had a surgical implant placed in his brain, which means he can now send a brief electrical pulse (about 130 times a second) to an area in his brain the size of a grapefruit pip. This controls his shaking.

The technique, called deep brain stimulation, has now become an established treatment for some people, like Mike, whose Parkinson’s doesn’t respond to medication.

The technology was developed after research on monkeys, whose brains have a similar structure to humans. The research helped identify the precise part of the brain associated with the shaking symptoms of Parkinson’s.

This type of brain surgery has potential risks, but research on 30 monkeys over 10 years showed it was likely to work and be relatively safe in humans. Deep brain stimulation now helps about 30,000 people worldwide, including Mike.

Mike is delighted to be an example of someone whose life has improved dramatically as a direct result of animal research.

”I am extremely grateful for the animal research that has allowed me to live a normal life again. It has improved the quality of my life beyond measure.”

Read more about Parkinson’s disease, including the different ways it is treated.

‘I’m lucky I found a trial that was so right for me’

Karen Ayres has an aggressive form of multiple sclerosis (MS). The severity of her symptoms varies, but at their worst she was paralysed from the neck down.

”I was in a dire situation,” she says. Her doctor at the NHS Walton Centre for Neurology in Merseyside suggested she might be suitable for a clinical trial of a combination of treatments. One was a form of chemotherapy often used in cancer treatment, and the other was a medication already used for MS.

It was an untested and risky option. The chemotherapy part of the treatment posed a small but definite risk of leukaemia, and it was uncertain whether or not the combination would do any good.

”My doctor was very open and honest about the risks. He emphasised that there was no guarantee that the combination would work, and that if it did, it wasn’t certain that any improvement would be sustained.”

Karen decided to take part in the trial. Her feeling that she was being told about the possible harms, as well as the benefits, helped her make her choice.

”I was running out of options,” she says. ”Even so, you have to go into a clinical trial hoping it will work, but knowing that it might not. You can’t go into a trial lightly – you need to know things and ask a lot of questions.”

She says she is fortunate to have been able to enter the trial. She was only the twelfth person to have the treatment. She also feels pleased to have been able, ”in a very small way”, to help find an effective treatment for some MS patients. ”I did my bit for science, and I hope the research will help other MS researchers.”