Skip main navigation
We use cookies to give you a better experience, if that’s ok you can close this message and carry on browsing. For more info read our cookies policy.
We use cookies to give you a better experience. Carry on browsing if you're happy with this, or read our cookies policy for more information.

Skip to 0 minutes and 14 secondsThis is the story of a clinical trial that took place in 1747 on board a British Royal Navy ship. To test which was the best way to treat scurvy, the ship's doctor gave six different treatments that were recommend at the time to pairs of sailors.

Skip to 0 minutes and 33 secondsOne of these treatments was oranges and lemons. The two sailors who were given oranges and lemons recovered. This trial resolved the uncertainty and revealed which treatment was effective. Since 1747, things have changed of course. But even now, as in those days, the best way to address uncertainty about the benefits and draw backs of treatments is to do a clinical trial. Clinical trial, first point-- the plan of what will be done in a clinical trial, the protocol, must be formally approved-- not by the researchers who propose it, since they may have a conflict of interest-- but by an ethics committee with independent experts and representatives of citizens. Second point-- patients must be divided into groups.

Skip to 1 minute and 21 secondsPatients in one group receive the treatment being tested. Patients in the control group do not. In some cases, the control group will receive a placebo. An inactive preparation that is otherwise identical to the experimental treatment. However, when there is already a proven effective treatment, patients in the control group should receive the best treatments available. Patients are allocated to the groups at random. For example by drawing lots. This is called randomisation and it helps form groups that are similar so that when their results are compared at the end, differences are due to the interventions given and not to pre-existing differences. Third point-- in some trials, patients do not know if they're taking the treatment or the placebo.

Skip to 2 minutes and 9 secondsThis is called blinding and stops their expectations influencing the results. It is also helpful if the doctors do not know who's in the treatment or control group. This also prevents both deliberate and unintentional bias. This is called double blinding. Fourth point-- at the end of a trial, the results must be analysed by unbiased researchers who do not have a vested interest in the findings.

Skip to 2 minutes and 39 secondsFifth point. A double blind clinical trial must be replicated in other independent trials.

Skip to 2 minutes and 47 secondsSixth point-- it's not enough that the new treatment is shown to be more effective than the control. It must really improve patients' health. So its benefits and risks must be carefully evaluated to make sure the pros outweigh any cons.

Skip to 3 minutes and 9 secondsPitfalls and traps-- placebos should not be used when there are effective treatments already available. The comparison should be made with the best treatment available. So that the research results can be confidently used to guide practise, a trial must include patients for whom the treatment is intended. Children, elderly people, ethnic minorities, and women are too frequently excluded from research. Pitfalls can arise in evaluating if a treatment is effective. For example, although high levels of cholesterol are a risk factor for myocardial infarction, a new treatment aimed at reducing cholesterol cannot be considered effective in preventing myocardial infarction, unless it reduces mortality. Simply reducing cholesterol is not enough.

Skip to 3 minutes and 55 secondsA treatment must be evaluated for its ability to improve outcomes that are important to patients. There may be shortcomings in the design of clinical trials. The aim is not just to decide whether a new treatment is as effective as the current standard treatment. Clinical trials must be designed to show whether a proposed new treatment is better than the existing treatment. Patients want to know whether a new treatment is actually better, not just the same or simply no worse. The health of everyone can be protected and promoted by health care decisions that are informed by high quality health research and clinical trials.

Skip to 4 minutes and 33 secondsThe European Union, which sponsors clinical research on treatments of interest to patients and the public, can support better organisation, transparency, and independence of clinical trials.

Clinical trials

How are clinical trials conducted? This video charts the course of a modern clinical trial, from the setting out of a research protocol to the evaluation of a treatment’s benefits and risks.

Please note: this video contains loud music

Share this video:

This video is from the free online course:

Making Sense of Health Evidence: The Informed Consumer

Cardiff University

Contact FutureLearn for Support