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Year : 2016  |  Volume : 5  |  Issue : 1  |  Page : 1-2

Randomized control trial: An overview

Editor-in-Chief, Journal of Dental and Allied Sciences, Sinhgad Dental College and Hospital, Pune, Maharashtra, India

Date of Web Publication1-Jul-2016

Correspondence Address:
Jayant N Palaskar
Professor and Head, Department of Prosthodontics, Sinhgad Dental College and Hospital, Pune - 411 041, Maharashtra
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2277-4696.185186

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How to cite this article:
Palaskar JN. Randomized control trial: An overview. J Dent Allied Sci 2016;5:1-2

How to cite this URL:
Palaskar JN. Randomized control trial: An overview. J Dent Allied Sci [serial online] 2016 [cited 2023 Jan 30];5:1-2. Available from: https://www.jdas.in/text.asp?2016/5/1/1/185186

Randomized control trials (RCTs) are the most stringent way of determining whether a cause–effect relation exists between the intervention and the outcome.[1] The RCT is a trial in which subjects are randomly assigned to one of two groups: one (the experimental group) receiving the intervention that is being tested, and the other (the comparison group or control) receiving an alternative (conventional) treatment.[2] The two groups are then followed up to note if there are any differences between them in outcome. The results and subsequent analysis of the trial are used to assess the effectiveness of the intervention, which is the extent to which a treatment, procedure, or service does patients more good than harm.[2]

Any RCT should have a research hypothesis, which is not similar to a null hypothesis, should be specific, and its outcomes can be accurately measured and compared using suitable statistical tests. After research hypothesis is formulated, step by step protocol of the proposed methodology to be adapted during the study has to be written down as it can be then circulated to concerned researchers or guiding agencies to identify and correct any error before starting the study. A well-documented protocol also helps other researchers to review or analyze the study and its outcomes and may relate it to some unintentional errors in its methodology. The RCTs with errors can misguide health researchers. The main errors in RCTs may be due to bias, confounding, or chance. Biasis the deviation of results from the truth, due to systematic error in the research methodology.[2] Bias may be of two types: (a) Selection bias, which occurs when the two groups beingstudied differ systematically in some way, and (b) observer/information bias, which occurs when there are systematic differences in the way information is being collected for the groups being studied.[2] A confoundingfactor is some aspect of a subject that is associated with both the outcome of interest and the intervention of interest.[2] Chanceis a random error appearing to cause an association between an intervention and an outcome. The most important design strategy to minimize random error is to have a large sample size.[2]

There are several steps in conducting an RCT, all of which need to be considered while developing a protocol.[2] The first is to choose an appropriate sample of the population from which participants to be included in the study. Having measured relevant baseline variables, the next task is to randomize subjects into one of two (or more) groups, and subsequently to perform the intervention as appropriate to the assignment of the subject.[2] The predefined outcome measures should then be recorded and the findings compared between the two groups, with appropriate quality control measures in place to assure quality data collection.[2] Each of these steps, which can be tested in a pilot study, has implications for the design of the trial if the findings are to be valid.[2]

Errors in the RCT can have a significant impact on the interpretation of the results. Some important aspects of the trial are mentioned below which can be incorporated in designing any RCT:

  • Recruit sufficient number of sample population depending on the research hypothesis to make a generalized conclusion of the outcomes of the study
  • Randomized allotment of subjects to the intervention/control groups to eliminate any selection bias
  • Both groups will be treated identically in all respects except for the intervention being tested
  • Both investigators and patients will be blinded to which group a subject has been allocated
  • The investigator assessing outcome will be blinded to treatment allocation [2]
  • Patients are analyzed within the group to which they were allocated, irrespective of whether they experienced the intended intervention [2]
  • Analysis of result should primarily focus on the research question (hypothesis) of the trial and need not aim at finding statistically significant difference.

  References Top

Sibbald B, Roland M. Understanding controlled trials. Why are randomised controlled trials important? BMJ 1998;316:201.  Back to cited text no. 1
Kendall JM. Designing a research project: Randomised controlled trials and their principles. Emerg Med J 2003;20:164-8.  Back to cited text no. 2

  Authors Top

Jayant N. Palaskar


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