Table of contents

Part 3 - Practice: Improving Health

Chapter 10 Identifying Hazards and Communicating Risks

Risk Communication

Once a risk has been identified and quantified and methods of reducing it have been found, the information has to be communicated to the people at risk to allow them to understand their risk and take steps to avoid it. Communication is the exchange of information; good communication is the exchange of information in a way that the recipient understands what the sender intends (Figure 10.2). A model of communication that was derived from a mathematical model of communication technology is useful as a basis for thinking about interpersonal communication. This model distinguishes six elements in the communication process: the message, the messenger, the encoding, the channel, the decoding, and the recipient.

Figure 10.2: The communication process showing the relationships between the elements of communication

The message

How risk is perceived depends on a number of factors besides the actual level of risk. Factors that influence risk perception can be related to the hazard itself (the exposure) or to the possible effects of the hazard (the outcome). The psychological state of the person perceiving the risk, as well as his socio-cultural background, can modify his perception of the hazard and of its potential effects. Factors that increase the perception of danger are listed in Table 10.8.

Table 10.8: Factors that increase public perception of danger11,12

Characteristics of Exposure


Not under personal control

Unnatural (e.g., terrorist attack)


Inequitable distribution of risk and benefit (people who suffer the consequences experience no gain from the activity)

No trust in institutions involved

Media attention

Characteristics of the Outcome

Catastrophic (instead of chronic)

Affects children or future generations

Unknown or uncertain outcome

Affects identifiable people, not statistics

Dreaded outcomes (e.g., cancer)

Immediate (vs. delayed)


Media attention

These characteristics can transform a minor statistical risk into a major perceived risk. For example, approximately 3,000 people were killed in the 9/11 attacks, whereas every year the U.S. typically experiences over 40,000 deaths related to road traffic incidents; many Americans were understandably distraught after 9/11, but deaths on the roads hardly attract any attention. From Table 10.8, the difference in reaction was due to the unfamiliarity of the events; they were beyond the control of even the U.S. government; they were catastrophic and attracted a great deal of media attention; they caused the simultaneous death of many identifiable people. By contrast, road traffic fatalities are familiar, under the control of road users, and don’t affect many people at any one time. To use a less dramatic example, in 2007 there were 0.012 deaths per million miles flown on U.S. commercial airlines compared to 0.91 deaths per million vehicle miles in urban areas and 2.27 deaths per million vehicle miles in rural areas, yet air travel frightens us more than driving along a country road.

Table 10.8 also explains why some people worry about environmental risks yet refuse to change their own high-risk lifestyles. For example, smokers can be anxious about small environmental risks that they cannot control, while continuing to ignore the great risk of smoking. Many patients fear taking medication even though they are assured that it could help their health problem; they see taking pills as unnatural, unfamiliar and with possible, uncertain secondary effects.

An effective message contains more than simple information; it also implies what the recipient should do with the information. For example, after discussing the risks and benefits of exercise with a patient, a clinician should conclude by relating this information to the patient’s personal situation and making it clear that the patient should take more exercise.

The Messenger

People respond more to the attitude of the messenger than to his or her status as a professional or authority. People tend to disregard information given by a recognized expert if he shows a lack of caring or empathy (Figure 10.3). By showing commitment to a listener’s well-being and by appearing honest, non-experts may influence listeners far more than an expert who disregards the emotional side of communication.

Figure 10.3: Personal qualities of the messenger and their relative effect on how the message is received

The recipient

The recipient is an active participant in communication. The recipient’s prior knowledge, beliefs, and attitudes affect his understanding of the message. When communicating with patients, a clinician needs to adapt the message to the patient. Several personal characteristics are likely to affect how a patient interprets the message:

General disposition

Optimistic people tend to feel at low risk. Pessimistic people, and those who are anxious or depressed, tend to overestimate risk and they perceive more threat than optimistic people. They are, therefore, more inclined to use defence mechanisms to reduce feelings of threat. This can go as far as denying the risk entirely.

Affective forecasting

Most people tend to be unrealistically pessimistic about how they will cope with situations they have not experienced. A person who, while still healthy, declares that she would prefer not to be resuscitated if it seems likely that survival might result in serious disability, may have a change of attitude once diagnosed with a serious illness; later she may find that she is better able to cope than she originally thought. In the same way, patients’ assessment of the risks and benefits of cancer treatments may vary with the evolution of their emotional state after they learn of the diagnosis.

Perception of threat

Most people feel that they have a lower-than-average chance of getting a severe illness. When shown information about the average risk, people tend to adjust their estimate of their own risk in response and so maintain the belief that they are at less than the average risk. This perception is more pronounced when the health problem is seen as controllable, is likely to occur in the distant future, and occurs in a type of person that the patient considers different from himself. The young smoker believes he has control over his smoking, knows that he is unlikely to feel the effects of smoking for many years, and does not yet consider himself a smoker; he is very unlikely to believe himself at risk of a smoking-related illness.

Confirmatory bias

People are more inclined to retain information that supports their prior beliefs than dissonant information. Cognitive consistency is powerful: even the most objective researcher has a tendency to focus on information that supports his hypothesis. A patient who believes his risk of cancer is low can be inclined not to believe that he has a cancer, or may minimise its significance. Clinicians are inclined to retain their preliminary diagnoses, even in the presence of contrary evidence.

Reduction of vulnerability

The need to feel invulnerable can make people deny or forget information about personal risk. In judging evidence that they are at risk, people may counter the information by questioning the validity or reliability of the source. Similarly, a patient receiving bad news is more likely to request a second opinion than a patient receiving good news. People also tend to find contrary examples to corroborate their denial, so smokers remember their grandfather who smoked twenty cigarettes a day and died in full health at the age of eighty-five.

The channel

The usual channel for clinical communication is the spoken word: clinician and patient talk to each other. However, words can be supplemented with visual aids, such as posters, leaflets, and, occasionally, videos. The recipient must have access to the channel of communication: written materials may not reach people who have difficulty reading.

Encoding and decoding

Information must be coded before it can be passed on. The code might be a language, scientific jargon, or slang; it can also take the form of an illustration or a diagram. For communication to be successful, the messenger and the recipient must share a common understanding of at least part of the code. Even though a clinician speaks the same language as the patient, differences in socio-economic milieu, education and experience can limit their common vocabulary. When a physician discusses an appendectomy with a patient, the physician is talking about a routine procedure that the patient is likely to recover from in a few days. The patient, on the other hand, is hearing about an alarming and unique experience that is likely to be painful, will leave a permanent scar, and will disrupt life for, at the very least, several days.

When communicating with their patients, clinicians should:

  • use words and concepts that their patients can understand,
  • remember that clinicians are familiar with medical conditions and procedures, whereas their patients are not,
  • modify their tone and body language to conform to the common code, as well as be aware that gestures may mean different things in different cultures. In North America, a Greek who shakes his head may be asking a question, not saying "no," while an Italian gesturing for someone to come closer may appear to be waving goodbye.

Information about risk is often coded as numbers or graphs. Most people can grasp the information in these forms, but there are a number of common pitfalls:

Emphasis on gain versus emphasis on loss

People tend to be averse to loss and will do more to avert a perceived loss than to achieve a gain. A well-known experiment describes responses to two sets of options for an imaginary disease:13 600 people are affected by a fatal illness, and we must choose between two forms of treatment:

Treatment A will save 200 people.

Treatment B has a one-third possibility of saving all 600 people, and a two-thirds probability of saving no one.

Most people opt for Treatment A because the prospect of saving 200 lives is more attractive than the possibility of losing 600, even though the mathematical value of the two choices is equivalent—200 versus one-third of 600. However, when Treatment A is expressed as a loss

Treatment A will allow 400 people to die.

Treatment B has a one-third possibility of saving everyone and a two-thirds probability that all 600 will die.

Most people opt for Treatment B because the one-third possibility of saving everyone is more attractive than the certainty of losing 400. The two sets of choices are mathematically equivalent, but loss aversion affects the choice. The way the choice is formulated is called the ‘frame’ and, to ensure informed choice, a clinician should communicate the information using a number of alternative frames.

Frame: in relation to …

Frame: in relation to communication and decision-making refers to the decision maker’s understanding of the acts, outcomes, and contingencies associated with a particular choice.13 Mentioning specific aspects of the risks and benefits can alter the patient’s frame and influence their choice.

The default option

The option that is presented as the usual one is more likely to be chosen than the one presented as the alternative.

Numbers versus proportions

Data expressed as proportions tend to be seen as relatively benign, whereas data expressed as a frequency tend to engage people much more. In one experiment, the case of a mentally disturbed patient was presented to physicians. They were told that 20 out of 100 patients similar to this one were likely to commit an act of violence. They were then asked if they would discharge the patient, and 41% said they would not. Another similar group of physicians was presented with the same scenario, but told that the patient had a 20% chance of committing an act of violence: only 21% of these physician refused discharge.

Glass half full or glass half empty

Emily and Ian are psychology students. In the last exam, both answered all the questions: Emily got 74% correct while Ian got 26% incorrect. Which is the better student? It is usually found that positive framing leads to positive feelings and negative framing leads to negative ones, so Emily is usually judged to be better than Ian. In discussing the risk of Alzheimer’s disease, dwelling on the 8% of people over sixty-five years old who have it gives a worse impression of the situation than dwelling on the 92% of people who don’t.

People don’t come in halves

People are more at ease with whole numbers, so fractions and decimal places should be avoided. Few estimates of risk or of therapeutic benefit are so precise that they merit decimals.

Numerator and denominator

People tend to focus on the numerator and ignore the denominator. A disease which afflicts ten in a hundred people tends to be seen as less common than one which afflicts a hundred in a thousand people. When discussing a single risk with a patient it can be helpful to express it in several ways: 10%, or one in ten, or ten in a hundred. However, when asking people to compare risks of different outcomes, one should keep the denominator constant. It is difficult for most people to understand the difference between one in five risk of one outcome and a 25% risk of another outcome. They will find it easier if a 20% risk is compared to a 25% one or if a one in five risk is compared with a one in four risk.

Relative and absolute risk

Relative risks may be particularly difficult to interpret because people do not always know the context; this is another example of the distinction between the patient and the population perspectives. Although hormone replacement therapy doubles the risk of breast cancer, it causes only eight additional cases of breast cancer in 10,000 woman years. For an individual woman, doubling the risk does not increase it greatly because the baseline risk is so small, whereas, on a population level, a doubling of the risk may be significant. It is advisable to use only absolute risks when communicating with individuals, because proportional changes may often obscure a lack of substantive importance.14

Patient Decision Aids. …

Patient Decision Aids.

It is often difficult to communicate the notion of risk to a patient in a readily comprehensible way. Annette O’Connor developed a series of patient decision aids as a practical tool to help patients choose between multiple options, each with different risks and benefits. See


In communication, uncertainty can occur for several reasons:

1. Words can be ambiguous and their meaning can vary. Clinicians should make certain that their patients understand the precise meaning of the possible outcome and the course of action suggested. If numbers are used instead of words, be aware of the biases inherent in a positive versus a negative framing of the statistics.

2. Terms to describe risk, such as high or low, are open to varying interpretation.

3. The definition of the risk may lack specificity. The risk should always include a time frame. A 10% chance of death from a lung cancer over a lifetime is not the same as a 10% chance in the next five years. A 20% chance of loss of function could be interpreted as a 20% reduction in function, or that 20% of people will have complete loss of function, or that 20% of people will have some loss of function.

When discussing risk with the patient, the information should be communicated in different ways, with both positive and negative framing, to help the patient arrive at a fully informed decision.

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