Clinical trials and research


Clinical trials and research


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.

Why carry out research?

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.


How is research funded?

the Medical Research Council (MRC)

the Department of Health and other government departments 

medical research charities 

pharmaceutical and other healthcare companies

However the research is funded, the people who take part in it are protected in the same way.

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.

The main types of health research are explained below.

Clinical 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.


Computer models

It's now possible for computers to try to simulate how the human body works, just as a computer game can imitate the way a car works.

As the human body is extremely complicated, computer models are currently unable to give reliable findings about how the body really behaves. However, they are already giving useful first suggestions to researchers.

The smoking and lung cancer link

In the 1940s, there were different theories about why there had been such a rapid rise in lung cancer over the previous 30 years.

An initial study of 700 people admitted to hospital with lung cancer revealed that nearly all were smokers. The proportion was much higher than for patients admitted to hospital for other reasons.

A careful follow-up study of 40,000 doctors over three years strengthened the evidence of a link, and convinced healthcare professionals of the dangers of smoking.


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.