Perception of risk of blood transfusion: knowledge, group membership and perceived control

The aim was to explore the perceptions of risk and choice behaviour associated with blood transfusion, within four key societal groups, namely general practitioners (GPs), anaesthetists, health/lifestyle journalists and blood donors. The study comprised a series of cross-sectional survey assessments incorporating a one-way between groups. Eighty-eight GPs, 141 anaesthetists, 20 journalists and 250 blood donors participated. The main outcome measures were perceptions of risk associated with blood transfusion (and nine other hazards, e.g. smoking) and whether or not participants, given the choice, would choose to have a transfusion of donated blood or a blood substitute. Level of knowledge formed a third main outcome variable. In terms of rank order, all respondent groups rated the risk of transfusion relatively realistically. That is, they perceived it as very low compared, for example, with smoking or driving a car. Levels of perceived risk about transfusion were associated primarily with subjective knowledge (a sense of what it is felt that people know) rather than objective (what people actually know). This relationship indicated that the more people felt was known, the less risk they perceived. Furthermore, participants were up to five times more likely to choose a blood substitute if they perceived a high level of risk associated with blood transfusion. All groups (especially journalists and blood donors) were under-confident with respect to their objective knowledge about transfusion (i.e. they knew more than they thought they did). Transfusion risk was perceived as relatively low. Objective knowledge was not associated with perceived risk for a transfusion. It is argued that facts on blood and transfusion should be presented in a manner that is congruent with the type of information being presented.