Investigating the psychological impact of communicating epistemic uncertainty in personalized and generic risk estimates: an experimental study

Nowadays, there is an increased availability of online health risk calculators aimed at providing people with personalized risk estimates of experiencing a medical disease. Despite being deemed as more relevant and useful than generic risk estimates, personalized risks are intrinsically imperfect and inherently uncertain, arising from limitations in the reliability, credibility, and accuracy of probability estimates (i.e. epistemic uncertainty). However, whether epistemic uncertainty around personalized risk estimates should be communicated to people is a topic of debate. In this pre-registered and conceptual replication study, participants (N = 239) were randomized to a 2 [Type of risk: personalized, generic] x 2 [Uncertainty: yes, no] between-subject design, in which they read a hypothetical scenario of a person who wanted to know his/her risk of developing colorectal cancer. Half of the participants used an online risk calculator for receiving a personalized risk, and half received a generic (non-personalized) risk of colon cancer. Furthermore, half of the participants received uncertainty information through a range estimate (‘5% to 13%’), and the other half received no uncertainty information by using a point estimate (‘9%’). Primary outcome measures were perceived risk and cancer-related worry. Perceived credibility was measured as a potential mediating variable, while subjective numeracy and health literacy were serving as control variables. People who received personalized cancer risk estimates reported lower risk perceptions and cancer worry compared to people who received generic cancer risk estimates. However, communicating risks with epistemic uncertainty led to higher risk perceptions than communicating risks without uncertainty, but only for those who received personalized risks. Such an interplay was not found for generic risk estimates. Overall, these interaction effects were not mediated by perceived credibility. In conclusion, psychological effects of disclosing epistemic uncertainty around risk estimates may only be applicable to individualized disease risk information.