Intensive Care Medicine

, Volume 32, Issue 12, pp 2020–2025

Informed consent in clinical trials in critical care: experience from the PAC-Man Study

  • Sheila E. Harvey
  • Diana Elbourne
  • Joanne Ashcroft
  • Carys M. Jones
  • Kathryn Rowan



To identify the proportion of critically ill patients able to consent to participation in a randomised controlled trial (RCT) and to assess to what extent patient consent and relative assent processes could be conducted according to ethics committee permissions.


Descriptive study nested in an RCT.


Fifty-six UK intensive care units participating in the PAC-Man trial.

Patients and participants

First 500 patients consecutively enrolled into PAC-Man.

Measurement and results

The outcome measures were patient consent and/or relative assent. Of the 498 patients included, 13 (2.6%) provided consent before randomisation. Of the remaining 485 patients, relative assent was obtained for 394 patients (81.2%), and refused post-randomisation for 3 patients (0.6%). No relatives were available for 15 patients (3.1%), and it was unclear from documentation whether relative assent had been obtained for 73 patients (15.1%). Of the 482 patients who did not provide consent prior to randomisation, 188 (39%) survived. Of these, 175 (93.1%) gave retrospective informed consent, six (3.2%) refused, and seven (3.7%) did not regain mental competency.


A very small proportion of patients were able to give consent before randomisation. Due to the high in-hospital mortality (60.6%), only around one third of the remaining patients could provide consent retrospectively. This study demonstrates difficulties experienced in obtaining consent from critically ill patients to participate in medical research and raises important issues about the ethical basis of the consent process in critical care.


Intensive care Clinical trial Ethics Consent 

Supplementary material

134_2006_358_MOESM1_ESM.doc (49 kb)
Electronic Supplementary Material is available in the online version of this article at and is accessible for authorized users.


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Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  • Sheila E. Harvey
    • 1
  • Diana Elbourne
    • 2
  • Joanne Ashcroft
    • 3
  • Carys M. Jones
    • 4
  • Kathryn Rowan
    • 1
  1. 1.Intensive Care National Audit & Research Centre, Tavistock HouseLondonUK
  2. 2.Medical Statistics UnitLondon School of Hygiene & Tropical MedicineLondonUK
  3. 3.UK Mental Health Research NetworkUniversity of ManchesterPrestonUK
  4. 4.Intensive Care UnitRoyal Berkshire HospitalReading, BerkshireUK

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