Understanding Uncertainty

“Spiegelhalter” actually is a German word that can be translated into “mirror holder”. David Spiegelhalter (2008) did exactly that for us. He held a mirror in which we could see us and could not see us at the same time. Do we really understand uncertainty? How do we handle it? Is it something we have to live with? Does knowing, that different kinds of uncertainty exist, help? How do we communicate uncertainty?

Different uncertainties

In his article, Spiegelhalter (2008, p.196) talks about “pure aleatory uncertainty” (chance) on the one side and “epistemological uncertainty” (evidence based) on the other side. He points out that the language of probability applies to both forms and that they may subjectively be perceived very differently. When telling somebody that there is a 50% chance of relapse for the disease she or he has, this is usually based on epistemological studies. In these studies, large samples (populations) are examined to determine the probability with which a certain event (e.g.; the relapse) occurs or does not occur. The quality of these studies is determined by how well they meet current methodological standards (e.g; control of variables, analyses used, statistical power). The results of these studies are statements about the likelihood of events, which rarely reach 100% for either one case or the other. One result, for example, might be that in the group of examined patients, the relapse rate was 50%. Does this group result tell us anything about a certain individual though? No. We simply do not know if the patient, who is sitting in front of us, will belong to the 50% that will not relapse or that will relapse. Can we communicate that? Yes. If a patient wants to know what is “chances” are, an answer is expected. Spiegelhalter (2008, p.197) says that the “standard way” is to “[embed] a new individual in a population of similar people in whom the frequency of adverse events is known”. We can, therefore, tell the patient that in a group of other patients with similar characteristics, 50% relapsed – but that we cannot tell him, if she or he will belong to those 50% or not. In this case, we communicate the epistemological uncertainty which – to the patient – might feel like pure aleatory uncertainty since a 50:50 chance very much resembles tossing a coin.

Interindividual Variability

Spiegelhalter (2008) put himself through the ARRIBA-Herz algorithm and found out that he has an 8% 10-year risk of a myocardial infarction (MI) or stroke which he compares to the chance of drawing an ace out of a pack of cards. Despite a 92% chance that he will not get a stroke or MI, he is still worried, finding comfort in the fact that the 8% risk is below average for his age. Why is he worried although his risk is so low? Why does he not go out and drink a beer to celebrate? What Spiegelhalter neglects in his article is the interindividual variability. We have to take into account that interpreting numbers and evaluating uncertainty is subjective – on both sides: the patient and the one who informs the patient. If we look at it from the side of the patients, being told that there is an 80% chance of relapse by two different people might sound very different. One might stress that 80% is really high and worrying and that precautions are vital; whereas another focuses on the 20% and stresses that there is still a good chance of not getting sick again. It becomes obvious that the personality and approach of the informant plays an important role. The same is true for the patient. Depending on personality, past experiences, and current state, two patients might interpret the same information given very differently. One might burst into tears, whereas the other feels relieved about “still” (in contrast to “only”) having a 20% chance of staying disease-free. These different reactions are not only due to different interpretations of the same information; different patient actually “hear” differently. Research focusing on the Fuzzy Trace Theory (Reyna, 2008) has shown that patients rely on gist representations of information. These kind of representations are vague and qualitative; they capture the bottom-line meaning of information, and they are subjective interpretations of information based on emotion, education, culture, experience, worldview, and level of development. What does that mean for the patient-informant relationship? It means that interpersonal skills are needed to successfully deal with different kinds of patients. Through interviewing, the informant can get a more detailed picture of how the information given was processed. In addition, the patients’ reactions tell us something about their needs (Who are desperate? Who give up easily? Who need support?), as long as the informant takes into account that she or he can trigger certain reactions by his or her way of presenting information . This “triggering” of reactions can actually be (and probably is) used as a tool. A patient with a laissez-faire attitude who, for example, does not see the point of changing his or her eating habits or taking his or her medication might be influenced by stressing the high risks of worsening his or her situation. But does the physician always know what is best for the patient? Is she or he the one to decide? At best, she or he can inform the patient about the possibilities, probabilities, and uncertainties. The final decision is the one of the patient, if she or he is capable of coming to one – even if that is to rely on the physician’s expertise.

The occurrence of “oddities”

How likely does an event have to be to become a possibility? If patients rely on physicians to tell them what the likelihood is to recover from a disease and what the possible treatments are, can they be sure to be told everything? Kolata (2008) claims that cancer researchers have known for years that it is possible in rare cases for some cancers to go away on their own. According to a study conducted by Welch, Zahl, and Maehlen (2008, as cited in Kolata, 2008), this might even happen more often than assumed. Their study “suggests that a significant number of cancers in the control group [over 100.000 women, who were not screened regularly] regressed and went away without treatment, but would have been detected with more frequent screening”. In the experimental group, also over 100.000 women were examined, but their regular screenings lead to a higher number of cancer diagnoses (invasive breast cancer) and treatments. Kolata (2008) cites Dr. Kaplan from the School of Public Health at the University of California. He says that “if the results are replicated […], it could eventually be possible for some women to opt for so-called watchful waiting, monitoring a tumor in their breast to see whether it grows, but people have never thought that way about cancer.” Depending on the way people “think” about a certain issue and depending on the epistemological information available, certain options might be excluded from the range of possibilities. Due to a low, maybe even very low likelihood of occurrence, these options might not even be mentioned by the informant, because they are considered “oddities”. Is this selection by the experts a “service” to the patient, because they keep track of the latest research findings and methods for him or her and do not overwhelm him with unfiltered information? Or is this a way of imposing a certain view upon him or her? Again, different patients will probably give different answers to these questions. Some might be thankful for not having to deal with any, far-fetched possibility; others might want to know all options.

A matter of choice?

Most of the above is actually not a question about right or wrong, but about how to process and present information. What sparks the person’s interest? Is it the symptom, the syndrome, the treatment, the usual, the exceptional, the group, the individual? The epistemologist focuses on the group and delivers group results. The physician has to focus on the patient, although she or he might perceive that patient as one of a group (e.g.; all patients with the same disease). The patient usually focuses on the physician, but can take other opinions into account; especially, when the physician is not considered to be the only authority. Nowadays, the internet can probably be considered as such, since patients inform themselves about what they have, might have, and how it should be treated, so that the physician has to justify him- or herself later. What all of the different groups have in common is, that they filter information and concentrate on certain aspects according to their socialisation. The epistemologist focuses on significant outcomes derived from (if she or he is lucky) huge samples, the physician concentrates on the diagnosis and the treatment, so does the patient. They all have different expectations and deal, yet, all with the same objective. Communication seems to be vital, but sometimes hard to achieve, because knowledge is acquired on different levels (group vs. individual). What makes it even more complicated, but also interesting are interindividual differences that do not allow for an ultimate solution.

References

Kolata, G. (2008). Some invasive breast cancers may go away on their own, researchers say [www document]. Recallable via: http://www.nytimes.com/2008/11/25/health/25breast.html [Access date: 03/16/09].

Reyna, V.F. (2008). A Theory of Medical Decision Making and Health: Fuzzy Trace Theory. Medical Decision Making, 28 (6), 850-865.

Spiegelhalter, D.J. (2008) Understanding uncertainty. Annals of Family Medicine, 6 (3), 196-197.

Welch, H.G., Zahl, P.-H., & Maehlen, J. (2008). The natural history of invasive breast cancers detected by screening mammography. Archives of Internal Medicine, 168 (21), 2311-2316.

Competing interests:   None declared