Introduction
Clinical trials attempt an objective search for truth or to get as close to the truth to provide evidence on a particular objective of investigation. However, elements of human behavior tend to introduce subjective bias, thereby diluting the veracity of such findings (Day & Altman, 2000). Randomization and allocation concealment are two elements of the research design that aim at reducing the influence of subjective bias on the results of the clinical study (Schultz & Grimes, 2002).
Randomization and Allocation Concealment
Randomization has become a popular method of limiting subjective bias of the participants or subjects in a clinical trial. The Consolidated Standards of Reporting Trials (CONSORT) statement also recommends its use in clinical trials (Campbell, Elbourne & Altman, 2004). Randomization consists of allocating the subjects at random to the different intervention groups, such that the subjects are unaware of which group they belong to. According to Simon, 2001, p. 146, randomization involves “a series of random numbers for assigning patients in a pattern that is inherently unpredictable”. However randomization by itself is insufficient to remove subjective bias and there is the need for proper allocation concealment. Allocation concealment refers to the concealment of the technique used for implementing the sequence of allocation and not the sequence used to generate it. Failure to have adequate randomization and allotment concealment could lead to exaggerated results in the clinical study (Schultz & Grimes, 2002).
However randomization and allocation concealment do get subverted in clinical trials for logical reasons and also because of human nature of the clinicians involved in the clinical trials. For ethical reasons it may not possible to use randomization in the case of some clinical trials, like clinical trials on smoking or HIV/AIDS. Instead the study may involve the study of the group as a whole or on the basis of observation or historical basis. The initial likely phase of subversion in randomization is in the selection of volunteers and the application of the inclusion and exclusion criteria. Physicians may choose volunteers that are likely to influence the study in the direction that they would like it to flow. Clinical studies involve volunteers and when studying a group of volunteers randomly assigned, there is the possibility of the volunteer group varying from the average general population and thereby reducing the validity of the clinical. In such clinical trials randomization may be avoided and the clinical trial conducted on observations or historical evidence off the general population. Subversion of randomization deliberately occurs when there are drop outs or non-compliers in the different subject groups, wherein such volunteers impact upon the treatment assignment by withdrawing themselves from the study or not complying with the treatment protocol assigned. Such drop-outs and non-compliers dilute the findings of the clinical study (Simon, 2001).
There are two other factors consisting of the human nature of clinicians that are likely to subvert randomization and allocation concealment. Clinicians are naturally curious and are uncomfortable randomizations conceals information that they would like to have. The second aspect is the challenge that this lack of knowledge poses to them and hence their efforts to subvert randomization and allocation concealment. Irrespective of whether their intentions are innocent or malicious, the end result is that it may affect the validity of the study (Schultz & Grimes, 2002).
Conclusion
Randomization and allocation concealment are two attempts at reducing subjective bias in clinical trials. Randomization cannot be used in all clinical trials. Furthermore either inadvertently or deliberately clinicians themselves reduce the effectiveness of these measures in reducing subjective bias
References
Campbell, M. K., Elbourne, D. R. & Altman, D. J. 2004, ‘CONSORT statement: extension to cluster randomised trials’, BMJ, vol.328, pp.702-708.
Day, S. J. & Altman, D.J. 2000, ‘Blinding in clinical trials and other studies’, BMJ, vol.321, pp.504.
Simon, S. D. 2001, ‘Is the Randomized Clinical Andrology Lab Corner
Trial the Gold Standard of Research?’ Journal of Andrology, vol.22, no.6, pp.146-154.
Schultz, K. F. & Grimes, D. A. 2002, ‘Allocation concealment in randomised trials: defending against deciphering’, Lancet, vol.359, pp.614-618.