What Are the Risks?
Ascertaining the pertinent risks is the first major challenge the physician faces in considering risk. Discussions of risks in medicine involve not only the chance of death but a myriad other outcomes (eg, vegetative state after cardiopulmonary resuscitation, incontinence following surgery for localized prostate cancer, missed subarachnoid hemorrhage in a patient with a new headache).
Understanding pertinent risks, however, does not mean simply knowing the identity of the risks; the concept of risk has several fundamental dimensions, and explicit consideration of these dimensions may facilitate more appropriate discussions (Table 1).
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Table 1. Five Basic Dimensions of Risk
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What Are the Pertinent Unwanted Outcomes?
Identification of pertinent unwanted outcomes is the first task of the physician in approaching medical risk and requires objective description of the outcome of interest (eg, death, disability, pain). The identity of the outcomes is often determined by the activity that provokes the risks. For example, the chance of dying from playing sports is low, but the risk for certain injuries may be reasonably high, such as knee injuries in football. In medicine, there may be several easily identifiable risks associated with an action, ranging in severity from mild (eg, minor nausea or pain) to moderate (eg, complication requiring further therapy and time lost from work) to severe (eg, death).
Identifying the pertinent unwanted outcomes will be difficult if some or all of the risks are not known or fully understood in a given situation. In some situations, one may even have to decide whether a given outcome represents a risk or benefit. For example, chemotherapy might allow a person to live longer with an otherwise incurable cancer. This added life expectancy might be a benefit to some people but for others, the extra time spent in discomfort would be a risk. Most of the time, however, the benefits and risks will be clear. Living longer and having a better quality of life are benefits whereas dying sooner and developing pain or loss of function are unwanted outcomes.
How Permanent Is the Unwanted Outcome?
The permanence or duration of an unwanted outcome is a second dimension of risk—one that may tip the balance in favor of or against a certain course of action. Some unwanted outcomes may be permanent (eg, death) whereas others may be transient (eg, pain). For the appropriate benefit, many patients may be willing to face a high chance of severe impairment as long as it will be transient, but may balk if the impairment will be long lasting or permanent. In the case of surgery for prostate cancer, the possibility of permanent incontinence or impotence may sway some patients to favor watchful waiting.
When Will the Unwanted Outcome Occur?
The third dimension of risk is its timing. Outcomes may occur very soon (eg, not surviving an operation, becoming nauseated following administration of medicine), in several months (eg, restenosis of a cardiac vessel following angioplasty), or in several years (eg, developing a blood malignancy from aggressive chemotherapy of a previous cancer). For example, patients with multivessel coronary artery disease are often faced with a difficult decision; surgical therapy results, on average, in improved life expectancy in the long run, but complications may lead to early death or significant short-term morbidity. The patient may be trying to balance present benefit with future risk or, conversely, may be deciding whether to accept significant present risk for possible future benefit. In economically derived models of health care decisions, such as cost-effectiveness models, one of the key assumptions is that time in the present is more valuable than time in the future and, hence, future benefit is "discounted." But the weight given to something that happens now as opposed to in the future is a highly individual function, and models based on the average will not be meaningful to many patients.
How Likely Is the Unwanted Outcome?
The fourth dimension of risk is its probability (ie, how likely is the unwanted outcome?). This number is known with varying degrees of certainty for different risks,4 and errors in the quantitative assessment of risks may be common.5 For physicians, this number may simply be difficult to remember. Additionally, the distinction between risk due to a single exposure and cumulative risk from multiple exposures may have to be considered. Probability may be the most difficult element to communicate in an understandable way to many patients.
How Much Does the Unwanted Outcome Matter to the Patient?
The fifth—and perhaps most important—dimension of risk is its value to the patient; that is, its subjective "badness." Different patients will inevitably rate some adverse outcomes differently. What one person views as catastrophic may be viewed by another as an impediment that does not detract from overall quality of life. The ultimate determination of importance is subjective.
The first 4 fundamental dimensions of risk—identity, permanence, timing, and probability—may help patients determine a personal value for the risk. In general, the value of most risks is closely allied with their identity. For example, death and mutilation are usually considered risks of great importance, whereas transient nausea would usually be considered a risk of relatively low significance. A risk may seem more tangible to a patient if it is serious and has a high chance of occurring in the short term. On the other hand, risks with a low chance of occurrence or those that would happen in the distant future may seem more nebulous or less threatening, even serious risks, such as death. Because the probabilities can often be very small, risks may not be conceptually accessible to patients trying to make decisions.
The value placed on a risk may be partly explained by concepts of risk perception developed by Slovic,6 in which risk is arranged along 2 axes relating to dread and uncertainty. Dread risks, such as nuclear reactor accidents, are uncontrollable, catastrophic, and not equitable, whereas risks from things like caffeine or aspirin are controllable, individual, and equitable. Uncertain risks, such as those from nitrogen fertilizers, are not observable, unknown to those exposed or the scientific community, and delayed, in contrast with risks such as automobile crashes, that are observable, known to those exposed and the scientific community, and immediate. Although they are derived from mostly nonmedical technologies, the concepts of dread and uncertainty may help explain why patients fear some medical risks, even those that are uncommon, more than others that are far more common.
Failure to acknowledge and discuss a patient's perceptions of risk may lead to decisions that both the patient and physician later see as unsatisfactory. For example, a woman without risk factors might choose mammography at age 40 years because of a morbid fear of breast cancer and then regret the trauma of a false-positive mammogram and its attendant stressful evaluation. It is the responsibility of the physician, as the most valued giver of information, to facilitate understanding of risk by addressing potential errors or biases in perception and to help place individual risks within the context of all risks and benefits for all alternatives in a given situation.
Which Risks Should Be Discussed?
Selecting the risks to discuss is the second challenge in risk communication. The physician must judge whether to address all conceivable risks, just the most common risks, or only the most important risks. For example, one can discuss the global level of risk from playing football, including injury, medical cost, and time lost from study or work, or a specific outcome, such as muscle aches, knee injuries, or deaths. The former approach has been called a thick conception of risk; that is, a conception that comprises a broad range of harms, including social losses and costs; the latter approach has been called a thin conception of risk, focusing only on physical harm.7
Regardless of the viewpoint, different treatments will carry different risks. How should physicians decide which risks to disclose? Various standards have been espoused, including the professional standard, in which the information that would generally be disclosed by a community of medical peers sets the standard, and the increasingly recognized reasonable person standard, in which the information that a reasonable person in the patient's position would want to be told sets the standard.1 Neither standard explains precisely how a physician should decide what a reasonable person would want to be told. Disclosure may vary depending on the unusualness of the procedure and the probability of the outcome, although risks of death, disability, and disfigurement generally should be revealed.1
How Should a Physician Discuss Risks With a Patient?
The way a discussion is framed may help determine the decision a person reaches,8-11 and features such as the physician's tone of voice or body language or the choice of what information to present first may influence the patient's perception of risk. Even the language chosen may contain loaded terms that can jeopardize unbiased communication. Risks may be considered avoidable or unavoidable, justifiable or unjustifiable, acceptable or unacceptable, serious or nonserious, or rare or common.12 For example, what seems acceptable to one person may seem unacceptable to another (eg, whether impotence following prostate surgery is serious or not depends on individual perspective).
Qualitative vs Quantitative Probability.
While the nature of an unwanted outcome must be described qualitatively, the probability can be described either qualitatively (eg, with terms such as rare or infrequent) or quantitatively (eg, with expressions such as "1 in 100"). Some patients may prefer to hear only qualitative descriptions of numerical probability, whereas others would like to "be given the numbers."13-14 Qualitative descriptions of probability have the attraction of using common words that seem to be generally understood.15 However, these words, of which there are many, have no generally accepted anchoring at specific quantitative levels of frequency,16 despite efforts to promote such an anchoring.12, 15 Whether the variability in interpretation of qualitative terms is enough to be clinically important is controversial. A rare outcome may deserve close attention if it is death, but a rare outcome that is minor may require no further quantification.
Quantitative Expressions for Risk.
The imprecise nature of qualitative expressions of risks has led some authors to urge that they be avoided and that risk information be imparted with strictly numerical expressions.17-18 There are many options for such expressions, including absolute or relative differences in the proportion of an outcome with 2 treatments, the frequency with which an outcome occurs in a certain cohort size, the average loss of life expectancy from a given exposure,19-20 the so-called safety-degree scale (the logarithm of the cohort size in which 1 adverse event would be expected to occur),21 and the number needed to treat22-24 (the reciprocal of the absolute difference in proportions of patients with a given outcome from 2 treatments or actions, which states the number of patients who must be treated to generate 1 outcome).
Beyond the question of whether patients will understand the difference between relative and absolute differences or the meaning of average loss of life expectancy, there is the complementary issue of which expression to choose. Simply altering the choice of a numerical format can change preference for one course of action instead of another, even if the 2 courses of action have quantitatively identical outcomes.8, 10 For example, outcomes can be framed in terms of survival rates or mortality rates; a death rate of 10% may seem quite different from a survival rate of 90%. As another example, a glass half empty may be perceived differently from a glass half full, and there will usually be a preference for the latter. Fortunately, in this instance there is a neutral description that is often lacking in discussions of medical risks (the 8-oz glass has 4 oz of liquid in it).7
The framing of outcomes in terms of absolute and relative differences10 can be manipulated to make a course of action appear more or less favorable or unfavorable. A relative risk reduction of 50%, for example, is less impressive when derived from the percentages 0.5% and 1.0% than from the percentages 25% and 50%. Furthermore, many physicians appear not to appreciate the distinction between absolute and relative differences,25-26 a failure that impedes the confident and correct communication of quantitative risk information.
Additional Challenges
Common Errors in Risk Interpretation.
As noted herein, patient perception of risk is a complicated phenomenon, laden with personal values and biases that challenge attempts to ensure the "correct" interpretation of risk information (Table 2).17, 27-28 For example, patients are subject to anchoring bias, in which patients estimate their own risk from a given action based on another familiar risk; availability bias, in which patients overestimate a risk that receives substantial notoriety (eg, in the media); compression, whereby patients overestimate small risks and underestimate large risks; and miscalibration of confidence judgments, which leads to overconfidence in the extent and accuracy of knowledge.27 Simply altering the scale in which a risk is placed can alter the perceived risk.16, 29 Finally, the perceived lethality of an activity and the perceived invulnerability of some individuals may lead them to assess their own level of risk as less than the risk to others from the same activity.27
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Table 2. Common Errors in Risk Estimation
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Given the diverse difficulties in understanding risks, people frequently resort to powerful heuristic guides, or rules of thumb, that provide convenient shortcut answers to probability questions, answers that are themselves probabilistic in being right most but not all of the time.30 These common interpretive errors pose tremendous challenges to physicians who may be struggling to define the risks and present them in accessible terms for patients from diverse backgrounds.
Reconciling the Average and the Individual.
The biggest challenge may be to help patients reconcile averages derived from populations and their meaning at an individual level. For example, although lower serum cholesterol levels result in a reduction in the number of myocardial infarctions in a large population of patients, an individual patient may be chagrined to learn that he is paying a lot of money and possibly experiencing a reduction in his quality of life for a very small chance of individual benefit. Or, a patient may face a given treatment with the reassuring advice from a physician that the chances of a serious complication are only 1 in 100, but he/she may remain very concerned about whether he/she will be that 1 in 100. The angioplasty patient does not experience a 4% myocardial infarction complication; for each individual patient, the outcome is an all-or-none phenomenon. Thus, even if we can identify and describe risks, the information must ultimately be expressed in terms that are meaningful to individual patients and must allow them to make decisions with which they are comfortable.
Patient Preference and Frameworks for Medical Decision Making.
Two related issues overlying any discussion of medical risk and implicit throughout this article are the ascertainment of patient preference and the choice of a framework for medical decision making.1, 31-32 Patient preference may vary not only for the relative value of diverse outcomes but also for the amount and type of information patients want to be given, the manner in which it is given, and the degree to which they participate in and control the decision-making process. The physician may be inclined to prefer 1 of several different frameworks for decision making, ranging from one in which the paternalistic physician controls the decision to one in which patient and physician share responsibility or to one in which the autonomous patient entirely controls the decision. Yet another framework that may assume more importance in the era of managed care is one in which some decisions are removed from the realm of the patient-physician relationship all together and claimed as the prerogative of corporate entities. Although a full discussion of these issues is beyond the scope of this article, we believe that ascertaining patient preferences and fostering a participative mode of decision making are of paramount importance for most situations in the practice of medicine.
NEW POSSIBILITIES FOR RISK COMMUNICATION
