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Understanding people’s ‘unrealistic optimism’ about clinical research participation
  1. Hae Lin Cho,
  2. David Gibbes Miller,
  3. Scott Y H Kim
  1. Department of Bioethics, National Institutes of Health Clinical Center, Bethesda, Maryland, USA
  1. Correspondence to Dr Scott Y H Kim;{at}


Background Researchers worry that patients in early-phase research experience unrealistic optimism about benefits and risks of participation. The standard measure of unrealistic optimism is the Comparative Risk/Benefit Assessment (CRBA) questionnaire, which asks people to estimate their chances of an outcome relative to others in similar situations. Such a comparative framework may not be a natural way for research participants to think about their chances.

Objective To examine how people interpret questions measuring unrealistic optimism and how their interpretations are associated with their responses.

Methods Using an early-phase cancer trial vignette, we administered the CRBA to 297 adults from the general public. They estimated their comparative chances of risk and benefit (7-point scale: −3 less likely to +3 more likely), then provided rationales for their estimates.

Results For both CRBA benefit and risk questions, about 50% of respondents chose 0 (the ‘correct’ response of ‘average likelihood’), and 50% chose a non-0 response. Respondents’ rationales for their estimates showed that overall only about 40%–44% gave comparative rationales, indicating that they interpreted the CRBA as intended. 68.7% of respondents who gave the ‘correct’ 0 rating gave comparative rationales, whereas only 11.6% of respondents who gave non-0 ratings did so. A similar trend was seen for chances of risk (p<0.001 for both).

Conclusion Research participants may not understand comparative benefit and risk questions as intended; attributions of unrealistic optimism may require additional evidence that the respondents’ estimates are intended to be comparative.

  • ethics
  • informed consent
  • unrealistic optimism
  • therapeutic misconception
  • clinical trials as a topic

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  • Contributors SYK initially conceived the idea for the project. HLC, DGM and SYK contributed to the design, data collection and analysis. HLC wrote the first draft of the manuscript. All three authors contributed to manuscript revision.

  • Funding This research was supported by the Intramural Research Program at the National Institutes of Health Clinical Center.

  • Disclaimer The opinions expressed in this paper are the authors’ and do not represent the views or policies of the NIH, DHHS, or the US government.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval This anonymous survey was deemed exempt from federal research regulation requirements by the National Institutes of Health Clinical Center.

  • Provenance and peer review Not commissioned; externally peer reviewed.