The use of unequal randomisation in clinical trials — An update.

Journal article


Peckham, Emily, Brabyn, Sally, Cook, Liz, Devlin, Thomas, Dumville, Jo and Torgerson, David J. 2015. The use of unequal randomisation in clinical trials — An update. Contemporary Clinical Trials. https://doi.org/10.1016/j.cct.2015.05.017
AuthorsPeckham, Emily, Brabyn, Sally, Cook, Liz, Devlin, Thomas, Dumville, Jo and Torgerson, David J.
Abstract

Objective To update a 2005 review of the reasons researchers have given for the use of unequal randomisation in randomised controlled trials (RCTs). Main measures Intervention being tested; type of study; number of participants; randomisation ratio; sample size calculation and reason given for using unequal randomisation. Methods Review of trials using unequal randomisation. Databases and sources Cochrane library, Medline and CINAHL. Results A total of 86 trials were identified. Of these 82 trials (95%) recruited patients in favour of the experimental group. Various reasons for the use of unequal randomisation were given including: gaining treatment experience; identification of adverse events; ethical; logistic and enhancing recruitment. No trial reported explicitly used it for cost-effectiveness. Most of the papers (i.e. 47, 55%) did not state why they had used unequal randomisation and only 38 trials (44%) appeared to have taken the unequal randomisation into account in their sample size calculation. Conclusion Most studies did not mention the rationale for unequal allocation, and a significant proportion did not appear to account for it in the sample size calculations. Unlike the previous review economic considerations were not stated as a rationale for its use. A number of trials used it to enhance recruitment, although this has not been tested.

Objective
To update a 2005 review of the reasons researchers have given for the use of unequal randomisation in randomised controlled trials (RCTs).

Main measures
Intervention being tested; type of study; number of participants; randomisation ratio; sample size calculation and reason given for using unequal randomisation.

Methods
Review of trials using unequal randomisation.

Databases and sources
Cochrane library, Medline and CINAHL.

Results
A total of 86 trials were identified. Of these 82 trials (95%) recruited patients in favour of the experimental group. Various reasons for the use of unequal randomisation were given including: gaining treatment experience; identification of adverse events; ethical; logistic and enhancing recruitment. No trial reported explicitly used it for cost-effectiveness. Most of the papers (i.e. 47, 55%) did not state why they had used unequal randomisation and only 38 trials (44%) appeared to have taken the unequal randomisation into account in their sample size calculation.

Conclusion
Most studies did not mention the rationale for unequal allocation, and a significant proportion did not appear to account for it in the sample size calculations. Unlike the previous review economic considerations were not stated as a rationale for its use. A number of trials used it to enhance recruitment, although this has not been tested.

KeywordsUnequal randomisation; Randomised controlled trials
Year2015
JournalContemporary Clinical Trials
PublisherElsevier
ISSN15517144
Digital Object Identifier (DOI)https://doi.org/10.1016/j.cct.2015.05.017
Web address (URL)http://hdl.handle.net/10545/622278
hdl:10545/622278
Publication datesNov 2015
Publication process dates
Deposited13 Mar 2018, 09:21
Rights

Archived with thanks to Contemporary Clinical Trials

ContributorsUniversity of York and University of Manchester
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