Common design concepts in randomized controlled trials.

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Author: Bolaji Egbewale
Date: March-April 2020
From: Nigerian Medical Journal(Vol. 61, Issue 2)
Publisher: Medknow Publications and Media Pvt. Ltd.
Document Type: Article
Length: 3,072 words
Lexile Measure: 1630L

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Byline: Bolaji. Egbewale

It is a known fact that Randomized Controlled Trials (RCTs) are the gold standard design methods in medical investigations particularly when the aim is comparison of medical therapies or effectiveness of intervention between treatment groups. This design method, once carefully followed, presents the highest level of evidence attainable in the measurement of treatment effect. Oftentimes, researchers confuse concepts related to the design of RCTs and thereby jeopardizing its benefits. Furthermore, in resource-poor settings, a very limited access to educational materials on design, conduct, and reporting of clinical trials exists. This among other reasons explains why most studies in such settings are observational in nature as RCTs are not as popular. This review adopted a narrative synthesis approach to aggregate current knowledge scattered in literatures in respect of selected common design concepts in RCTs so as to elucidate on their meaning and demands. Overall, 25 literatures drawn majorly from the PubMed database including 8 textbook materials were involved in examining the following concepts; Study Population in RCTs Setting, Primary and Secondary Outcome Measures, Single and Multicenter Trials, Pragmatic and Explanatory trials, and Blinding. Appropriate search terms for each of the concepts were entered into the PubMed database and relevant articles accessed. This review article, intended for educational purposes could also serve as a guide, especially for new entrants, in the design of RCTs. It is hoped that this educational material would contribute immensely toward maximizing the benefits of this all-important design method.


Indeed Randomized Controlled Trials (RCTs) offer solutions to some of the issues that have been raised against observational studies, for example, treatment effect identified by observational studies are prone to methodological weaknesses such as selection bias and confounding.[1],[2] However, this assertion is only correct for a well-designed RCT. A clear understanding of design concepts and procedures in a controlled trial by researchers is very germane to a successful experiment. Such concepts and procedures are what define and distinguish a RCT from observational studies. A successfully designed RCT requires a succinct reporting on how such procedural concepts have been carried out at the design stage of the experiment, and thus, the need for trial researchers to be well informed on their demands and requirements. Furthermore, the risk of bias associated with particular RCT study is graded based on such information. This review attempts to aggregate current knowledge scattered in literatures in respect of selected common design concepts in RCT so as to elucidate on their meaning and demands. It is anticipated that this article would provide helpful hints for educational purposes and also contribute immensely to enhancing the design of future controlled experiments.


A narrative synthesis of selected common concepts in RCTs was adopted in this review. Search for appropriate literatures was conducted electronically and manually where necessary. Overall, 25 reference materials including articles and books on the selected concepts were drawn from different literature sources: library text materials, and mostly, PubMed database. Appropriate search terms for each of the concepts to be reviewed were...

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Gale Document Number: GALE|A623903193