Promoting Ethical Design and Data Integrity for Cluster Trials: Issues of Consent

Project Summary

Cluster randomized controlled trials (cRCTs) are increasingly popular in health services research. Our project is looking at the research ethics of these trials.

What is a cRCT?

  • A “randomized controlled trial” (RCT) is a type of research study that tests a new treatment, procedure, practice, etc (i.e., an “experimental intervention”). To do this, RCTs randomly assign participants to either keep doing what they did before (e.g., do their usual treatment) or try something new (e.g., start a new, experimental treatment).
  • A “cluster randomized controlled trial” compares “clusters” of people instead of individual people. “Clusters” might be different hospital wards or clinics.


For example, a new handwashing protocol may be assigned to half the hospital wards while the other wards continue to do their old handwashing protocol. The study mainly collects data about health care providers’ handwashing behaviour, but also looks at whether infection rates in hospital units that use the new protocol differ from the ones that are not using this new protocol.


How are we studying cRCTs?

We’re asking: who should be required to provide consent for these different trials? Clinic or hospital administrators? Doctors and other care team members involved? Patients?

To investigate these questions, we conducted a systematic review and qualitative interviews to explore patients’, cRCT researchers’, and research ethics boards’ perspectives on ethical consent processes for different types of cRCTs.

Based on our findings, we are developing a framework and online module to guide researchers and research ethics boards on ethical design of cRCTs, with emphasis on issues of consent.

Project Findings

Our preliminary findings suggest that these questions are challenging to navigate.

  • Some believe that the data in clinical databases should be available without explicit consent for data to be used in research, as long as patient safety, privacy, and confidentiality is maintained
    • But how can we judge if this safety, privacy, and confidentiality has been met?
    • Interviewees also emphasized that, even if there is a waiver of consent and no consent process, there should still be an information process to respect the participants
  • Some believe that waiving individual consent for cluster trails that pose little to no harm can be acceptable, especially if seeking individual-level consent can incur undue burden on the research team
  • Some suggested instituting a “gatekeeper” who has the best interests of participants in mind
  • Questions arose around how to distinguish between cluster trials and quality improvement projects
  • Participants voiced a need for guidelines that are more focused on patients’ perspectives, not only health system perspectives
    • We will develop patient-oriented guidelines upon completion of our data analysis

Our data analysis is ongoing. We are currently in the process of producing video and educational modules on our findings and on questions around ethical cluster trials more generally.


We will be presenting these preliminary findings to a virtual patient feedback group later this month. For more information, please email Dr. Anita Ho ( by March 18, 2022.

This project is part of the Real-World Clinical Trials Cluster.


Anita Ho, PI
John (Kip) Kramer, Co-PI
Kathryn Banks
Mike Burgess
Pia Ganz
Holly Longstaff
Michael McDonald
Danielle Behn Smith
Soodi Joolaee
Don Grant
Michele White
Eirikur Palsson
Mariko Ikeda