The availability heuristic and health

Risk comprehension is sometimes thought to be driven by the availability heuristic (Links to an external site.), whereby people falsely rationalize that because they can easily think of an example of a particular event happening, that it is actually likely to occur. The classic illustration of this phenomenon is someone having a greater fear of death in a plane crash versus in a car accident, despite the relatively greater risk of death occurring by the latter. Perhaps this disproportionate fear is because plane crashes are more commonly in the news, or because they are comparatively more severe – but the reality is that most people spend more time in cars than in planes. There is a disconnect between the examples that are easily brought to mind and perhaps draw some emotional power over us, and those that serve to give us an accurate sense of risk.

This phenomenon also applies generally to health risks. Knowledge of our individual risks comes from many places – the media, family, friends, interaction with a clinician, etc. Epidemiologists characterize health risks in terms of large groups of people, so we know our average risk. One reason that individuals are not good at realistically identifying their own health risks is that describing risks on the population level cannot fully capture the unique combination of risk factors which are important for an individual. This could be your family history of cancer, lifestyle, and diet, among others. Some women may assume that they are at greater risk for developing breast cancer than heart disease (the #1 killer of women (Links to an external site.)). Perhaps they had a close female relative or friend with breast cancer, or fear a prolonged illness. Another plausible explanation is that breast cancer awareness has been a hugely successful public health initiative: It makes the news, and we are asked to wear pink, hug a survivor, and run for the cause. The availability heuristic strikes again?

What do you think the role of individual perception plays on recognizing health risks? Do you think the availability heuristic is a logical explanation, or is there more to the story? What other factors might impact our ability to understand them and to act in ways to manage our health risks?

Now applying what you’ve learned from the readings and videos, let’s go through the rest of the discussion together, one question at a time. This discussion will reference the required reading, “The decision-making process in prostate cancer screening in primary care with a prostate-specific antigen: A systematic review (Links to an external site.). Vedel, I., Puts, M.T.E., Monette, M., Monette, J., Bergman, H. 2011. J Geriatric Oncol. 2(3):161-176.

There have been many success stories of population-wide screening programs. There is no doubt that routine screening of blood donations for various infectious diseases, mammography, and cholesterol blood tests have collectively saved millions of lives compared to conducting no screening for these conditions. The flip side of these success stories is the many people whose screening led to unnecessary and sometimes stressful diagnostic testing to determine that they were not in fact diseased. As you participate in this discussion, consider the characteristics of diseases suitable for screening and those of good screening tests. Recognize how these characteristics drive discussions about screening efficacy and the use of a particular screening test.

Roughly 25% of men who have a prostate biopsy due to an elevated prostate-specific antigen (PSA) level actually have prostate cancer. A false positive screening test result could be a frightening prospect for a patient. How do you feel about a policy that recommends all men over 50 be PSA-screened?
One argument against the evidence in support of widespread PSA screening is that results from population-level studies do not apply to individual patients. If you were a physician treating a concerned patient who is concerned with this point, what would you say as a counterpoint, given what you have learned about population level screening? Where do we draw the lines between efficiency, risks, and benefits? Consider characteristics of screening suitability in your answer.