Intensive Care Medicine

, Volume 35, Issue 10, pp 1703–1712 | Cite as

Patients’ preferences for enrolment into critical-care trials

  • Damon C. Scales
  • Orla M. Smith
  • Ruxandra Pinto
  • Kali A. Barrett
  • Jan O. Friedrich
  • Neil M. Lazar
  • Deborah J. Cook
  • Niall D. Ferguson



Most critically ill patients are incapable of providing informed consent for research.


We sought to determine patients’ preferences for different consent frameworks for enrolling incapable patients into critical-care trials.


Prospective observational and structured interview study.


Five university-affiliated hospitals in Ontario.


Two-hundred and forty consecutive capable and consenting survivors of critical illness.


Participants considered four frameworks for enrolling incapable patients into clinical trials using a baseline scenario and three permutations for: risk (very low vs. high), treatment type (new vs. currently available), and availability of substitute decision-maker (yes vs. no).

Measurements and main results

For each scenario, patients chose their preferred framework and rated the acceptability of each framework using a seven-point Likert scale. Most (180/240; 76%) patients selected “consent by substitute prior to enrolment” as their preferred framework; this also received the highest baseline acceptability ratings (“acceptable” or “highly acceptable” 207/240; 87%). Modifying risk or treatment type did not substantially change these ratings. A minority of patients rated delayed consent as unacceptable or highly unacceptable in both the baseline scenario (48/240, 20% delayed to substitute; 57/240, 24% delayed to patient) and when a substitute was unavailable (34/240; 15%).


Most survivors of critical illness found the usual practice of obtaining informed consent from a substitute decision-maker prior to enrolment in a clinical trial to be acceptable. Nearly half of patients considered foregoing informed consent to be unacceptable, whereas a minority considered enrolment followed by delayed consent to be unacceptable even when a substitute was unavailable. These approaches should, therefore, only be considered when deviating from the usual practice of obtaining consent from a substitute decision-maker is truly justified, such as where treatments being tested need to be delivered as soon as possible in order to be effective.


Critical care Intensive care Informed consent Decision making Proxy Research design Ethics Research 



We thank Mardi Baum, Katie L. Chapman, Greer Kirshenbaum B.Sc, Shelley Kraus B.Sc, Amanda Y. Li B.Sc, Kristina Lutz B.Sc, Jonathan S. Rosenberg B.Sc, Mohana Ratnapalan, Jasmine Soliven, and Ellen McDonald RN for assistance with data collection; Andrea Tkaczyk RN for preparing the research ethics application at St Joseph’s Healthcare; Helen Michalopoulous RN, and Michael Ward MD for input into initial discussions on study concept and design; and Sean P. Keenan, MD, M.Sc, Ellen McDonald RN, Donald A. Redelmeier, MD, and Roxanne Ward RN for critical revisions to earlier versions of this manuscript. This study was funded by grants from the Physicians’ Services Incorporated Foundation and the Canadian Intensive Care Foundation. None of the funding agencies had any role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; or the preparation, review, and approval of the manuscript. Dr Scales served as a consultant for the Ontario Ministry of Health and Long-term Care Critical Care Strategy. Dr Friedrich is supported by a Canadian Institutes of Health Research Clinician Scientist Award. Dr Cook is a Research Chair of the Canadian Institutes of Health Research. Dr Ferguson is supported by a RCT Mentoring Program Award from the Canadian Institutes of Health Research. We also thank all the patients who consented to be interviewed for this study.

Conflict of interest statement

None of the authors has any conflict of interest to declare.

Supplementary material

134_2009_1552_MOESM1_ESM.doc (462 kb)
(DOC 461 kb)


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Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Damon C. Scales
    • 1
    • 2
  • Orla M. Smith
    • 3
    • 4
  • Ruxandra Pinto
    • 2
  • Kali A. Barrett
    • 2
  • Jan O. Friedrich
    • 1
    • 4
  • Neil M. Lazar
    • 1
    • 5
  • Deborah J. Cook
    • 6
    • 7
  • Niall D. Ferguson
    • 1
    • 5
    • 8
  1. 1.Interdepartmental Division of Critical Care MedicineUniversity of TorontoTorontoCanada
  2. 2.Department of Critical Care MedicineSunnybrook Health Science CentreTorontoCanada
  3. 3.Faculty of NursingUniversity of TorontoTorontoCanada
  4. 4.Critical Care and Medicine Departments, Li Ka Shing Knowledge InstituteSt. Michael’s HospitalTorontoCanada
  5. 5.Division of Respirology, Department of MedicineUniversity Health NetworkTorontoCanada
  6. 6.Departments of Medicine and Clinical Epidemiology and BiostatisticsMcMaster UniversityHamiltonCanada
  7. 7.Department of Critical Care MedicineSt. Joseph’s HospitalHamiltonCanada
  8. 8.Toronto Western HospitalTorontoCanada

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