Effects of comparative information when communicating personalized risks of treatment outcomes: an experimental study

Despite great promise of using personalized risks of treatment outcomes during shared decision-making, patients often experience difficulty evaluating and using them. We examined the effects of providing comparative information of the average person’s risk when discussing personalized risks on people’s cognitive, emotional, and behavioural responses. Participants (n = 1,807) from a representative sample of the Dutch population received personalized risks of treatment side-effects in three different health scenarios. Participants either received only their own personalized risk statistic, or with comparative data indicating that their risk was below or above average. Furthermore, we examined whether the effects would be influenced by message format (natural frequencies with or without icon arrays) and individual differences (subjective numeracy, health literacy, and graph literacy). Providing comparative information did not influence participants’ risk perceptions, affective evaluations, nor their treatment intention. However, participants who were told that their personalized risks were above average, estimated their own risk as lower than participants who received the same personalized risks that were below average or that were without any comparative data. Message format and individual differences did not influence people’s responses to comparative data. Healthcare professionals can consider providing comparative data for helping people make sense of their personalized risks.