PATIENTS' UNDERSTANDING OF THE TIME HORIZON OF HEALTH RISK

   Purpose. We examined how people cognitively combine three components of a preventive medical message – the likelihood of an adverse event or disease, the time horizon associated with this likelihood, and the patient’s personal time frame – in estimating their health risk and how they distribute this risk over the years of its time horizon.

    Methods. Fifty-four French adults aged 22-55 years were presented with 45 scenarios that described the content of a medical message supposedly directed to them about their risk of developing angina pectoris.  The scenarios were devised as a function of an orthogonal factorial design with three factors: likelihood of developing angina pectoris (10, 20 or 30 chances out of 100), associated time horizon (in the next 10, 15 or 20 years), and patient’s time frame (from now [2003] to 2005, 2007, 2009, 2011, or 2013). The question was: “What are, in your opinion, your chances of developing angina pectoris from now to [the year indicated in the third factor]”?

   Results. People’s estimated personal risk significantly increased as the likelihood of angina increased, as the time horizon for its occurrence decreased, and as the time frame on which the persons focused their attention increased. The subjective values they attributed to the two time factors during the information integration process were quite linearly spaced; that is, risk was spread evenly over the time horizon.

   Conclusions. When clinicians talk to patients about risk, they should be aware that people seem to be able to translate information about the probability of disease occurrence and its time horizon into their personal time frame, but may, without further direction, apportion their risk evenly over the time horizon.