Evaluation of a visual risk communication tool: effects on knowledge and perception of blood transfusion risk.

BACKGROUND: Effective risk communication in transfusion medicine is important for health-care consumers, but understanding the numerical magnitude of risks can be difficult. The objective of this study was to determine the effect of a visual risk communication tool on the knowledge and perception of transfusion risk. STUDY DESIGN AND METHODS: Laypeople were randomly assigned to receive transfusion risk information with either a written or a visual presentation format for communicating and comparing the probabilities of transfusion risks relative to other hazards. Knowledge of transfusion risk was ascertained with a multiple-choice quiz and risk perception was ascertained by psychometric scaling and principal components analysis. RESULTS: Two-hundred subjects were recruited and randomly assigned. Risk communication with both written and visual presentation formats increased knowledge of transfusion risk and decreased the perceived dread and severity of transfusion risk. Neither format changed the perceived knowledge and control of transfusion risk, nor the perceived benefit of transfusion. No differences in knowledge or risk perception outcomes were detected between the groups randomly assigned to written or visual presentation formats. CONCLUSION: Risk communication that incorporates risk comparisons in either written or visual presentation formats can improve knowledge and reduce the perception of transfusion risk in laypeople.