What is the PRISM visual tool measuring? Risk affiliation?

Perhaps for the first time, researchers have attempted to formally measure the risk perceptions of travelers compared with expert providers regarding health risks using a psychometric measuring instrument.1 However in both the original article and the associated editorial,2 there was no discussion or referencing of the vast body of knowledge from the field of risk perception within the greater context of risk research.3 Some of the findings from Zimmermann and colleagues1 using the PRISMvisual tool could easily be ascribed to established attributes of risk perception documented in the plethora of risk research falling outside of travel medicine. The purpose of this correspondence is to critique the lack of validation of this particular instrument for measuring attributes of risk perception. A coherent risk research agenda is also lacking within the International Society of Travel Medicine (ISTM)4 and the field of travel medicine in general.5 Zimmermann and colleagues used a visual psychometric measuring instrument to record travelers’ risk perceptions.1 This tool is called the ‘‘pictorial representation of illness and self measurement’’ or PRISM6 being successfully validated in the past,7 but solely in the context of subjective burden of suffering in patients with chronic diseases.8–10 The PRISM has never been formally validated in the context of evaluating risk perception in relatively healthy travelers.1 Therefore, it would have been useful for the researchers to have first validated this psychometric tool in the full context of travel medicine practice before conducting applied research and trying to draw conclusions from its findings. Suffering from a chronic disease is a subjective consequence of the condition, whereas riskmay be a perceived or technical measure of uncertainty about future events. Thus, the PRISM has been validated under a condition (ie, suffering from chronic disease), which is a very different phenomenon from the concept of risk. For this visual tool to be considered validated for use in the field of travel medicine, PRISM results need to be compared with the results of other validated methods for measuring risk perception. While there are many models for explaining risk perception, the most popular are the ‘‘psychometric paradigm’’11 and ‘‘heuristics-and-biases’’ approaches.12 Two potential effects of risk perception may be influencing the PRISM in the recent study, namely the risk attributes of familiarity compared with dread13 and the cognitive bias of unrealistic optimism.14 Typically in other risk research findings, ‘‘accidents’’ and sexually transmitted infections (‘‘STIs’’) are perceived as more familiar and less dreaded risks,15–18 whereas ‘‘terrorist attacks’’ and vaccine-related adverse events (‘‘VAEs’’) may be perceived as less familiar and more dreaded risks.19,20 Even if an individual has a greater affiliation with familiar risks (eg, ‘‘accidents’’), the person may also feel less concern about such a risk because it is perceived as less dreaded compared with exotic risks.11 In Figure 3 of the Zimmermann article, the general trend of results from the PRISM’s ‘‘self-risk separation’’ or SRS (ie, stated as a proxy for risk perception) appears to be increasing for both the traveler and the expert, from more familiar and less dreaded risks (eg, ‘‘accidents,’’ ‘‘mosquitoes,’’ and ‘‘STIs’’) to less familiar and more dreaded risks (eg, ‘‘terrorist attacks,’’ ‘‘epidemic outbreaks,’’ and ‘‘VAEs’’). If the SRS was a valid measure for risk perceptions, one would expect the SRS to measure this trend in the opposite direction, as per established risk research within other fields.3,11,13 For example, injury prevention programs typically find low ‘‘outrage’’ or perceived risk for common accidents, such as motor vehicle collisions15 and sporting injuries.16 The problem here may partly be related to the PRISM having solely been validated for ‘‘self-illness separation’’ (ie, the distance between ‘‘self’’ and the patient’s illness), which is inversely proportional to the perceived importance of a chronic illness and not a travel-related risk.6,7 The authors have made an untested assumption that the PRISM will also measure perceived risk, as it does for subjective suffering.1 This last point is important if we want to use any specific psychometric tool to make observations and corresponding conclusions about pre-travel risk management and risk communication strategies. Are we really measuring risk perceptions among travelers and experts, or are we measuring something else? In the case of PRISM, wemay simply bemeasuring a person’s affiliation with a given risk in the samemanner as it is used to measure a person’s affiliation with an illness or chronic symptom that is part of their ongoing suffering.6–10 If so, then the SRS may not be measuring the important characteristics of risk perception that motivate people to take preventive action or inhibit them from addressing travel-related risks (eg, dreaded vs not dreaded, imposed vs voluntary, man-made vs natural, etc.).3,11,13 Some of the results1 may also be affected by unidentified heuristics (ie, mental shortcuts) leading to observable cognitive biases as described in the ‘‘heuristics-andbiases’’ approach.11,21 For example, some differences in SRS scores between the experts and traveler for certain risk categories may be partially explained by unrealistic optimism or ‘‘optimistic bias.’’14 The PRISM results suggest that travelers are less concerned about contracting STIs compared with the expert providers, yet there is good medical evidence that STIs are a significant