Treatment allocation in controlled trials why randomise

Randomized clinical trials RCTs are widely used as the gold standard for comparative medical studies. Using randomization to determine treatment assignment assures that all patients have the same … Expand. View 1 excerpt, cites background. Fundamentals of Randomization in Clinical Trial. Rapid, easy, and cheap randomization: prospective evaluation in a study cohort. View 2 excerpts, cites background.

Influence of selection bias on the test decision. A simulation study. Methods of information in medicine. Treatment allocation in controlled trials: why randomise? Minimisation: the platinum standard for trials?

Practical statistics for medical research. Mathematics, Computer Science. Epidemiologic surveillance in developing countries. Annual review of public health.

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Search articles by 'D G Altman'. Altman DG 1 ,. Bland JM. Affiliations 1 author 1. A comment on this article appears in " Is recruitment more difficult with a placebo arm in RCTs? Methodological issues will have affected results. Share this article Share with email Share with twitter Share with linkedin Share with facebook.

Abstract No abstract provided. Free full text. PMID: By contrast, blinding relates to what happens after randomisation, is not possible in all trials, and seeks to reduce ascertainment bias assessment of outcome. National Center for Biotechnology Information , U.

Journal List BMJ v. Author information Copyright and License information Disclaimer. This article has been cited by other articles in PMC. References 1. Treatment allocation in controlled trials: why randomise? How to randomise. Schulz KF. Subverting randomization in controlled trials. Blinding in clinical trials and other studies. Medical Research Council. The 15th patient has factors sex female, 74 yr, and site 2.

If this patient is allocated to the control group, the total imbalance is 3. Although minimization is designed to overcome the disadvantages of stratified randomization, this method also has drawbacks.

A concern from a statistical point of view is that it does not satisfy randomness, which is the basic assumption of statistical inference [ 15 , 16 ]. For this reason, the analysis of covariance or permutation test are proposed [ 13 ].

The calculation process is complicated, but can be carried out through various programs. So far, the randomization methods is assumed that the variances of treatment effects are equal in each group. Thus, the number of subjects in both groups is determined under this assumption. However, when analyzing the data accruing as the study progresses, what happens if the variance in treatment effects is not the same? In this case, would it not reduce the number of subjects initially determined rather than the statistical power?

In other words, should the allocation probabilities determined prior to the study remain constant throughout the study? Alternatively, is it possible to change the allocation probability during the study by using the data accruing as the study progresses? If the treatment effects turn out to be inferior during the study, would it be advisable to reduce the number of subjects allocated to this group [ 17 , 18 ]?

An example of response-adaptive randomization is the randomized play-the-winner rule. That is, this method is based on statistical reasoning that is not possible under a fixed allocation probability and on the ethics of allowing more patients to be allocated to treatments that benefit the patients. However, the method can lead to imbalances between the treatment groups. In addition, if clinical studies take a very long time to obtain the results of patient responses, this method cannot be recommended.

As noted earlier, RCT is a scientific study design based on the probability of allocating subjects to treatment groups in order to ensure comparability, form the basis of statistical inference, and identify the effects of treatment.

However, an ethical debate needs to examine whether the treatment method for the subjects, especially for patients, should be determined by probability rather than by the physician. Nonetheless, the decisions should preferably be made by probability because clinical trials have the distinct goals of investigating the efficacy and safety of new medicines, medical devices, and procedures, rather than merely reach therapeutic conclusions.

The purpose of the study is therefore to maintain objectivity, which is why prejudice and bias should be excluded. That is, only an unconstrained attitude during the study can confirm that a particular medicine, medical device, or procedure is effective or safe. Consider this from another perspective. If the researcher maintains an unconstrained attitude, and the subject receives all the information, understands it, and decides to voluntarily participate, is the clinical study ethical?

Unfortunately, this is not so easy to answer. Participation in a clinical study may provide the subject with the benefit of treatment, but it could be risky. Furthermore, the subjects may be given a placebo, and not treatment. Eventually, the subject may be forced to make personal sacrifices for ambiguous benefit.

In other words, some subjects have to undergo further treatment, representing the cost that society has to pay for the benefit of future subjects or for a larger number of subjects [ 4 , 19 ]. This ethical dilemma on the balance between individual ethics and collective ethics [ 20 ] is still spawning much controversy. If, additionally, the researcher is biased, the controversy over this dilemma will obviously become more confused and the reliability of the study will be lowered.

Therefore, randomization is a key factor in a study having to clarify causality through comparison. Studies have described a random table with subsequent randomization. However, if accurate information on randomization is not provided, it would be difficult to gain enough confidence to proceed with the study and arrive at conclusions. Furthermore, probability-based treatment is allowed with the hope that the trial will be conducted through proper processes, and that the outcome will ultimately benefit the medical profession.

Concurrently, it should be fully appreciated that the contribution of the subjects involved in this process is a social cost. The details are beyond the scope of this study, and are therefore not covered.

The details are beyond the scope of this study. No potential conflict of interest relevant to this article was reported. National Center for Biotechnology Information , U. Journal List Korean J Anesthesiol v. Korean J Anesthesiol. Published online Apr 1. Chi-Yeon Lim 1 and Junyong In 2. Author information Article notes Copyright and License information Disclaimer.

Corresponding author: Junyong In, M. This article has been corrected. See Korean J Anesthesiol. This article has been cited by other articles in PMC. Abstract Randomized controlled trial is widely accepted as the best design for evaluating the efficacy of a new treatment because of the advantages of randomization random allocation.

Keywords: Adaptive randomization, Minimization, Random allocation, Randomization, Randomized controlled trial, Restrictive randomization, Simple randomization, Stratified randomization.

Introduction Statistical inference in clinical trials is a mandatory process to verify the efficacy and safety of drugs, medical devices, and procedures. Methods of Randomization The method of randomization applied must be determined at the planning stage of a study.

Simple randomization In simple randomization, a coin or a die roll, for example, may be used to allocate subjects to a group.