Randomized controlled trial

Sellers of medicines throughout the ages have had to convince their patients that the medicine works. As science has progressed, public expectations risen, and government health budgets been ever tighter, pressure has grown for a reliable system to prove this.

All medicines and surgical proceedures must therefore undergo trials before use. Effects of a treatment may be small, and biological organisms (including humans) are complex and do not react to the same stimulus in the same way. There is also a proven placebo effect. This can be marked, and powerful. Some conditions will spontaeously go into full remission - doctors for hundreds of years have reported miracle cures for no discernable reason. Finally, the simple process of administering the treatment may have direct effects on the patient.

Randomised trials can be open, blind or double blind.

In an open trial the researcher knows the full details of the treatment, and so does the patient. These trials are open to challenge for bias, and they do nothing to reduce the placebo effect. However, sometimes they are unavoidable, particularly in relation to surgical techniques, where it may not be possible to hide from the patient which treatment he received.

In a blind trial the researcher knows the details of the treatment but the patient does not. Because the patient does not know which treatment they are getting (the new treatment or the other treatment) there should be no placebo effect. In practice, since the researcher knows, they sometimes subconsiously hint to the patient which one it is.

In a double blind trial, one researcher allocates a series of numbers to 'new treatment' or 'old treatment'. The second researcher is told the numbers, but not what they have been allocated to. Since the second researcher does not know, they cannot possibly tell the patient, directly or otherwise, and cannot give into patient pressure to give them the new treatment. In this system, there will be a more realistic distribution of sexes and ages of patients.

Therefore double blind trials are preferred as they tend to give the most accurate results. This is the 'randomised' and the 'trial' element of this article covered.

The 'controlled' aspect comes from three main sources. The first is another member of the research team, who will typically review the test to try to remove any factors which might skew the results. e.g. it is important to have a test group which is reasonably balanced for ages and sexes of the subjects (unless this is a treatment which will never be used on a particular sex or age group). The second source of control is inherent in having a 'control' group i.e. a group which is undergoing the same routine (seeing a doctor, taking pills at the same time etc.) but is not having the same treatment. This control group will either be receiving no treatment (e.g. sugar pills) or will be receiving the current standard treatment (if, for example, it would be unethical not to treat their ailment at all). The third source of control is via peer review and/or review by government regulators who will examine the trial when it is presented for publication or when the drug manufacturer applies for a licence for the drug.

The importance of having a control group cannot be underestimated. Merely being told that you are receiving a miracule cure can be enough to cure patients - even if the pill contains nothing more than sugar. The proceedure itself can produce ill effects. For example, in a study on rabbits where they were receiving daily injections of a drug it was found that they were developing cancer. If this was a result of the treatment, it would obviously be unsuitable for testing in humans. Because this result showed equally in the controll group the source of the problem was investigated and it was shown that receiving daily injections was a cancer risk - not the drug itself.