Clinical trials: deliberations on their essence and value

In the context of the evidence-based medicine (EBM) movement, the clinical trial has come to be hailed as the ultimate source of medical knowledge, and especially of clinical pharmacology. By subjecting the premises of this procedure to a thorough analysis, the author hopes to achieve a sound rating of its epistemological significance in the context of medical research.

Current claims on the basic importance of the evidence provided by standardized clinical trials are confronted with conflicting observations concerning their current application in medical practice. The stereotyped trials of present research in multiple sclerosis serve as an example to illustrate this point.

Traditional assumptions concerning the validity of standardized clinical trials are based on an illusion of absolute objectivity and reliability. Apart from being subject to tough publish (conveniently)-or-perish and commercial influences, the results of clinical trials, especially drug trials, are of limited informative value in diverse respects, such as (i) clinical trials do not identify every possible drug reaction for every instance of a disease; (ii) their results never allow the prediction of the efficacy of a specific drug in any given individual; (iii) clinical trials have no inherent potential to provide concrete insights into the nature and cause(s) of a definite morbid condition; and (iv) extensions of clinical drug trials to ever-larger study groups indicate serious problems in basic theoretical respects.

A clinical trial cannot indicate a certain prevention or cure for any particular instance of a disease, and the correctness of its individual predictions is always only contingent. This can be explained by the fact that the correspondence between the nature of each of all pathological conditions presented by the different members of a clinical trial population and by the individual patients being treated according to the results of the trial is never complete.