Intended for healthcare professionals

Research Methods & Reporting

Consort 2010 statement: extension to cluster randomised trials

BMJ 2012; 345 doi: (Published 04 September 2012) Cite this as: BMJ 2012;345:e5661
  1. Marion K Campbell, director1,
  2. Gilda Piaggio, honorary professor2,
  3. Diana R Elbourne, professor of healthcare evaluation2,
  4. Douglas G Altman, director3
  5. for the CONSORT Group
  1. 1Health Services Research Unit, University of Aberdeen, Aberdeen AB25 2ZD, UK
  2. 2Department of Medical Statistics, London School of Hygiene and Tropical Medicine, London, UK
  3. 3Centre for Statistics in Medicine, University of Oxford, Oxford, UK
  1. Correspondence to: M K Campbell m.k.campbell{at}
  • Accepted 5 July 2012

The Consolidated Standards of Reporting Trials (CONSORT) statement was developed to improve the reporting of randomised controlled trials. It was initially published in 1996 and focused on the reporting of parallel group randomised controlled trials. The statement was revised in 2001, with a further update in 2010. A separate CONSORT statement for the reporting of abstracts was published in 2008. In earlier papers we considered the implications of the 2001 version of the CONSORT statement for the reporting of cluster randomised trial. In this paper we provide updated and extended guidance, based on the 2010 version of the CONSORT statement and the 2008 CONSORT statement for the reporting of abstracts.

Many journals now require that reports of trials conform to the guidelines in the Consolidated Standards of Reporting Trials (CONSORT) statement, first published in 1996,1 revised in 2001,2 and revised most recently in 2010.3 The statement includes a checklist of items that should be included in the trial report. These items are evidence based whenever possible and are regularly reviewed.4 The statement also recommends including a flow diagram to show the progression of participants from group assignment through to the final analysis. An explanation and elaboration of the rationale for the checklist items is provided in an accompanying article.4

The standard CONSORT statement focuses on reporting parallel group randomised controlled trials in which individual participants are randomly assigned to study groups. However, in some situations it is preferable to randomly assign groups of people (such as communities, families, or medical practices) rather than individuals. Reasons include the threat of “contamination” (the unintentional spill-over of intervention effects from one treatment group to another) of some interventions if individual randomisation is used.5 6 Also, in certain settings, randomisation by group may be the only feasible method …

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