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Researchers’ perceptions of ethical challenges in cluster randomized trials: a qualitative analysis

Andrew D McRae1*, Carol Bennett2, Judith Belle Brown3, Charles Weijer4, Robert Boruch5, Jamie Brehaut6, Shazia Chaudhry7, Allan Donner8, Martin Eccles9, Jeremy Grimshaw10, Merrick Zwarenstein11 and Monica Taljaard127

Author Affiliations

1 Division of Emergency Medicine, University of Calgary, Foothills Medical Centre, Rm C231, 1403 – 29 Street NW, Calgary, Alberta T2N 2T9, Canada

2 Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada

3 Centre for Studies in Family Medicine, Department of Family Medicine, The University of Western Ontario, London, Ontario, Canada

4 Department of Philosophy, Philosophy and Medicine, Rotman Institute of Philosophy, University of Western Ontario, London, Ontario, Canada

5 Education and Statistics, Graduate School of Education, University of Pennsylvania, Philadelphia, PA, USA

6 Ottawa Hospital Research Institute, Clinical Epidemiology Program, Ottawa Hospital, Ottawa, Ontario, Canada

7 Ottawa Hospital Research Institute, Clinical Epidemiology Program, Ottawa, Ontario, Canada

8 Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Canada

9 Clinical Effectiveness, Institute of Health & Society, Newcastle University, Newcastle upon Tyne, UK

10 Ottawa Hospital Research Institute Department of Medicine, University of Ottawa, Ottawa, ON, Canada

11 Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada

12 Department of Epidemiology and Community Medicine, University of Ottawa, Ottawa, Canada

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Trials 2013, 14:1  doi:10.1186/1745-6215-14-1

Published: 3 January 2013



Cluster randomized trials (CRTs) pose ethical challenges for investigators and ethics committees. This study describes the views and experiences of CRT researchers with respect to: (1) ethical challenges in CRTs; (2) the ethics review process for CRTs; and (3) the need for comprehensive ethics guidelines for CRTs.


Descriptive qualitative analysis of interviews conducted with a purposive sample of 20 experienced CRT researchers.


Informants expressed concern over the potential for bias that may result from requirements to obtain informed consent from research participants in CRTs. Informants suggested that the need for informed consent ought to be related to the type of intervention under study in a CRT. Informants rarely expressed concern regarding risks to research participants in CRTs, other than risks to privacy. Important issues identified in the research ethics literature, including fair subject selection and other justice issues, were not mentioned by informants. The ethics review process has had positive and negative impacts on CRT conduct. Informants stated that variability in ethics review between jurisdictions, and increasingly stringent ethics review in recent years, have hampered their ability to conduct CRTs. Many informants said that comprehensive ethics guidelines for CRTs would be helpful to researchers and research ethics committees.


Informants identified key ethical challenges in the conduct of CRTs, specifically relating to identifying subjects, seeking informed consent, and the use of gatekeepers. These data have since been used to identify topics for in-depth ethical analysis and to guide the development of comprehensive ethics guidelines for CRTs.

Cluster randomized trials; Research ethics; Informed consent; Clinical trials; Bioethics; Knowledge translation; Quality improvement; Implementation research