Health News

It is not really possible to isolate any single part of a trial process as being independent of any other part. The whole procedure depends upon every aspect relating to the overall requirement. There are, however, some basic comments which may be aimed at the selection of trial procedures for new substances of therapeutic value.

Before a decision on the precise form of trial to use in order to assess the therapeutic value of a new substance is made, it is essential that the specific characteristics displayed by the substances are recognized. A decision which causes an inappropriate trial procedure to be adopted can result in valuable therapeutic properties being missed. Unfortunately, such decisions happen, possibly because the present system of trials is at fault in being rather narrow in outlook. The two main forms of trials used to assess the therapeutic value of substances in live subjects are known as the double blind and the double blind crossover procedures.

The double blind trial is one in which two groups of patients are used. One group is treated with the substance under evaluation and the other group with a placebo. Neither group of patients, nor the doctors actively engaged in the trials, know which patients are receiving which treatment. To do this the ‘active’ substance and placebo are coded so that no one other than the person holding the code knows which is which. The purpose of the double blind is to minimize the chances of psychological influence and personal bias being involved.

The double blind crossover trial incorporates the same procedure except that, after a period of treatment, the patient groups have their treatment crossed over. This means that patients who first received substance ‘X’ will now get substance ‘Y’, and vice versa.

In both types of trial the code is not broken until the treatment process is completed. In this way no one knows which substance is doing what until the final results are analyzed.

There is little to criticize in the principle of these trial procedures, as long as we bear in mind the factors which can influence any trial work on living subjects. The double blind trial seems to be soundly based an uncomplicated. From an outside viewpoint this trial procedure would seem to be the best one available. The same cannot be said for the double blind crossover trial, however. This procedure has some characteristics which make it a mo unsuitable choice except, perhaps, in special cases. Perhaps we can clarify this suggestion by carrying out an imaginary double blind crossover trial of our own using one imaginary substance.

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