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This article is taken from The Health Matters Consumer Guides.
Published: 20/01/2005

How do you know why a doctor has chosen a particular treatment to give you over another? A hunch? A tip from a colleague? A wild guess?

The answer is, hopefully, because of the evidence that it works. That evidence comes in the form of a clinical trial.

A trial is a test to see whether a particular drug (or a surgical operation, or a diagnostic test for a condition, or a medical device) is safe, whether it works and whether it's better than the drugs, devices, or tests already available.

Usually, once a trial is complete, the results will be published in a medical journal. The information is then used by doctors and other health professionals to make treatment decisions, and also by the Pharmaceutical Benefits Scheme to decide whether the drug should be subsidised.

Clinical trials are run by universities, teaching hospitals, private research organisations or drug companies (often in conjunction with research institutions). Teams of doctors, nurses, pharmacists and other health professions supervise the participants through the whole process, and often afterwards. Trials are very strictly regulated – there's a host of conditions a trial must satisfy before it can go ahead. It must go before a Human Research Ethics Committee (HREC), a committee of experts who must be satisfied that there's a good reason to do the trial, that it's safe for the patients, and that the people associated with the trial are competent and qualified.

Phasing them in

There are different sorts of clinical trials depending what stage the drug (or treatment, device or test) is at. These stages are called phases.

  • Phase 1: This is the first trial of the drug on humans (up to this point, research will usually have been conducted on animals). Healthy volunteers are given the drug and observed by the trial team over the period of the trial. The aim is to find out whether it's safe (and at what dose), whether there are side effects, and how it's best taken (as tablets, liquid, or injection for instance).
  • Phase 2: If the drug passes muster in phase 1, it's next given to people who actually have the condition for which the drug was developed. The aim of a phase 2 trial is to see what effect the drug has – whether it improves the condition and by how much, and again, whether there are any side effects.
  • Phase 3: Phase 3 trials are similar to a phase 2 trial except the number of people given the drug is much larger. Again, researchers are looking at safety and effectiveness. Phase 3 is the last stage before the drug is then licensed for use by the general public.
  • Phase 4: In this phase, the drug is compared to other, existing, drugs. The idea of a phase 4 trial is to get more qualitative information – determining where exactly the drug is mostly useful, in what sort of patient. The participants in a phase 4 trial are people in the community who have the condition. How useful a phase 4 trial is can vary a lot. Those that are the most useful are those that are well designed. The design of a trial refers to the way that is structured so as to make the conclusion of the trial valid. For example, well-designed trials have a large sample size (meaning there are lots of people in the trial) and have a 'control group' (a group of people who don't receive the drug so that a comparison can be made). For an explanation on how trials are designed, go to our story on 'Making Sense of Health Information', which has a section on Clinical Trials.

    Should I join a trial?

    Why would anyone be so courageous (stupid?) as to try something that hasn't been thoroughly tested for safety? A good question. And there may be risks involved in joining a trial. But there are benefits too. Joining a trial may be way of getting early access to a new treatment that isn't widely available, especially for somebody with a serious illness for whom existing treatments aren't proving effective. Other people join a trial because the feel good about being involved in the development of a new, possibly life-saving drug.

    The negatives are: it can be a complete waste of time (the treatment doesn't work or you end up in the control group, getting a placebo (fake) treatment for comparison). Or you may get side effects. If this happens, you can leave or the trial may be stopped. If you suffer serious harm because of your involvement in a trial, the research organisation is legally obliged to pay you compensation.

    How do I join a trial?

    Sometimes research organisations advertise for people to join a trial. In other cases suitable participants are recruited through their GPs. Some web sites list trials that are open to new participants (though some of these are bogus and are actually fronts to sign people up to new medicines). For a list of web sites that list clinical trials, see the More info section at the end of this story.

    Informed consent

    Anyone who participates in a trial has rights. These are set out in the trial protocol, which must be approved by the ethics committee. You must be given a written explanation of the clinical trial by a doctor, explaining the possible risks and benefits, and details of any tests or procedures you might have to undergo.

    Involvement in a trial is voluntary. You can withdraw at any time (it's common for people to leave – often for trivial reasons, not just side effects from treatment). The trial team must respect your privacy and not disclose your participation or your results to anyone.

    More info

  • Making sense of health information: Health Matters Consumer Guide
    How to judge whether the latest 'breakthrough' is right for you.
  • National Health & Medical Research Council's Clinical Trial Centre
    Includes the National Clinical Trials Registry, which lists cancer trials and has a list of cancer trials open to participants.
  • Making sense of medical research
    An article on different types of clinical trials and how to interpret them. From Women's Health Queensland Wide, a non-profit health information and education centre.

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