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J Rheumatol. 2003 Apr;30(4):815-24.

Are subjects satisfied with the informed consent process? A survey of research participants.

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  • 1Department of Medicine, University of Western Ontario, London, Ontario, Canada.



Letters of information (LOI) for clinical trials are becoming longer and more complicated. We investigated patients' perspectives of their ability to understand the information presented during a clinical trial. Satisfaction with and motivation for participation in clinical trials were also ascertained. Perceptions from various treatment disciplines were compared.


Participants were chosen from 14 clinical trials (departments of rheumatology, ophthalmology, and cardiology) conducted at the same university. Subjects were asked to complete a written questionnaire that assessed demographic information, recall and understanding of information, subjects' decisions to participate, and perceptions/opinions of the study. The response rate was 75% (rheumatology, n = 74; ophthalmology, n = 32; cardiology, n = 84).


The majority of respondents (98%) indicated that they were satisfied with the informed consent process and with their involvement in a trial (97%). Subjects who reported having understood the LOI had better recall of placebo/active drug comparator (p < 0.03), and better understanding of why placebo was used (p < 0.04). No differences were found between those who reported understanding and those who did not on understanding the concept of concealed allocation (blinding). Subjects who felt they had received "the right amount of information" were more likely not to understand concealed allocation. The most frequent reason for trial participation was to help medical science (80%). Subjects with higher education were more likely to understand the reason for placebo use (p < 0.0003), but were not more likely to understand concealed allocation (p < 0.08).


Subjects reported that they were satisfied with the informed consent process and their experience in a clinical trial, and that they understood trial concepts. Subjects may be able to self-assess their own level of understanding for trial concepts that intrinsically make sense within the context of their beliefs about medical care, but other trial concepts may be misunderstood/misinterpreted regardless of self-assessment of understanding or education level (i.e., concealed allocation). Subjects may prefer to believe that investigators know which treatment they are receiving, and have made a good treatment decision specific to their case, despite having being told about concealed allocation and placebo use.

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