Preference Construction and the Psychology of Drug Risk/Benefit Assessments Paul Slovic With thanks to Ellen Peters and Robin Gregory Decision Research and University of Oregon pslovic@darkwing.uoregon.edu May 30,2006
Some Questions: 1.What does it mean to understand the risks and benefits of pharmaceuticals? 2.Why even ask this? --consumers have a right to know --liability issues --we patients think we would use this info for decisions though we rarely do --it is useful for monitoring adverse reactions
More Questions: 3.What is the problem we are addressing? 4.Will better understanding enhance patient decision making and welfare? How?
Questions continued: 5.What does it mean to consider risks and benefits( R/B)?To weigh R/B?To balance R/B? To trade off risks and benefits?
Some assertions: 1.To answer these questions we need to differentiate different types of judgments and decisions: a)decisions to initiate drug use b)decisions to terminate or continue use (adherence). c)monitoring judgments 2)Risk is not a well-defined concept,which can be a problem for communication(one of many problems).
What Is Risk? 1. Risks as hazards Which risks should we rank? 2. Risk as probability What is the risk of getting AIDS from an infected needle? 3. Risk as consequence What is the risk of letting your parking meter expire? Answer: Getting a ticket. 4. Risk as potential adversity How great is the risk of riding a motorcycle? Here, risk is some unspecified blend of probability and payoff. The language of risk is problematic!
Assertions contd. 3.Making tradeoffs is difficult.we rarely do it explicitly as a calculation.we behave in ways that allow our tradeoffs to be inferred. The rare exception is shown on the next slide.
Assertions continued: 4. a)initial use of a drug is very often decided by MD. b)continuation of use decided by many factors other than R/B: e.g.cost,sense of wellness, taste, convenience,etc. Is it making me feel better or worse? c)monitoring involves recognition,not R/B tradeoffs. So explicit R/B tradeoffs are rare.
5.When we are forced to confront tradeoffs we become uncomfortable.to escape the conflict we may use a simple rule to determine the decision,or we may avoid making the decision altogether (see e.g. research by M.F. Luce et al.).
6.We have to acquire R/B information before we can begin to process it. Many elderly patients cannot even do this, much less make tradeoffs.
Comprehension errors increase with age The Comprehension Index : Reflects number of errors made out of 35 decision tasks involving interpretation of tables and graphs Two Study Samples: Older adults aged 65+ (n = 253) Employed Age < 65 (n = 239) (Hibbard et al., 2001)
EXAMPLE OF DECISION TASK: HMO A HMO B HMO C HMO D Monthly Premium $50 $75 $48 $63 Copayment for office visit with primary care doctor $10 $5 $15 $10 1. Which HMO requires the lowest copayment for a visit with a primary care doctor?
Which HMO requires the lowest copayment? 38 % Errors 25 28 21 65-69 70-74 75-79 80 + Age
So,assuming we do acquire the information, how do we really make decisions involving risks and benefits? Answer:We often construct our preferences on the spot using a remarkable ensemble of mental strategies and heuristics, few of which involve calculating risk/benefit tradeoffs explicitly. The construction process is readily altered by subtle aspects of the decision context, which poses many practical and ethical challenges.
Forthcoming July 2006,documenting almost 40 years of research on the psychology of preference.
1. The Measurement Problem Meaningful measurement of physical qualities (e.g., weight, distance) requires the satisfaction of description invariance and procedure invariance. Measures of preference systematically violate both of these fundamental requirements. e.g.framing effects violate description invariance.
Description Invariance Different but logically equivalent descriptions of the decision problem should yield the same preference. Framing effects violate description invariance
Framing: Surgery vs. Radiation Therapy Treatment 1 year!!! 5 years % choice of radiation therapy Mortality rates Surgery Radiation 10% 0% 32% 23% 66% 78% 44% Surgery Survival rates 90% 68% 34% 18% Radiation 100% 77% 22% Source: B. McNeil et al., New England Journal of Medicine, 1982
How then should information be framed?
2. Procedure Invariance Different (but equivalent) measures for eliciting preferences should lead to the same preference ordering, just as different but equivalent measures of heaviness for example, placing two objects on opposite sides of a pan balance to see which is heavier versus measuring each object separately on a scale should yield the same ordering of weight.
(like choice) Which is heavier? Which is preferred?
How heavy is it? How much do you like it? How much would you pay for it? (like rating, matching, or pricing)
Preference measures often violate procedure invariance. Object A may be clearly preferred over object B under one method of measurement (e.g., choice), while B is clearly preferred under a different but presumably equivalent measurement procedure (e.g., matching or pricing). In what sense,then,do preferences really exist and how should they be measured?
Assertion: We may have clear,stable preferences For some general attributes(e,g,life,liberty, safe drugs, effective drugs,inexpensive drugs) and some simple,familiar goods(e.g.apple pie). But clarity and stability vanish when it comes to tradeoffs among even well-defined values.
Violation of Procedure Invariance: Early Studies Preference Reversals 1971-1973 P bet 35/36 win $4.00 $ bet 11/36 win $16.00 Many Ss choose the P bet but attach higher $ values (buying and selling prices; cash equivalents) to the $ bet. (Slovic & Lichtenstein, 1971 and 1973)
The Blossoming of Preference Reversals Measures of value prices choices Reversals demonstrated with a wide range of stimuli -new products -ice cream -job candidates -job offers -air quality -salaries -punitive damage awards by juries -countries in which to live (income distribution) etc.
Preference Reversal Between Joint and Separate Evaluations Work by Chris Hsee and Colleagues Whereas traditional preference reversals involve different types of responses (e.g., choices and prices), differences in response modes (e.g., joint evaluation JE vs. separate evaluation SE) also produce reversals.
Kahneman and Ritov (1994) found that, in JE, people would contribute more to programs that save human lives (e.g., farmers with skin cancers), but in SE, they would contribute more to programs that save endangered animals (e.g., dolphins)
Hsee and Zhang (2004) demonstrate that, in JE, people overpredict the differences that different values of an attribute (e.g., different salaries) will make to their happiness in SE. This is called distinction bias. Predicted utility experienced utility.
Construction of Preference: The Broader Perspective Emerges Over a period of 35 years, the study of preference reversals has led to a method for documenting a broad, encompassing view of human behavior that has come to be known as the construction of preference.
The thesis of preference construction is that we often do not know our own values and must construct them on the spot, using not only our knowledge, feelings, and memory, but also many aspects of the current environment, including how the preference question is posed and what type of response is required.
Some elements of preference construction: Go with the Status quo Defer to a trusted advisor(e.g.your MD). Go with the default rule(e.g.organ donation study) Eliminate by aspects(lexicographic rule) Prominence rule(e.g.choose what s best on most important dimension) Framing Editing/ Dominance structuring Rely on reasons Rely of feelings(affect) Miswanting Decision Utility vs. Predicted Utility vs. Experienced Utility Immune Neglect Duration Neglect
Elements of Preference Construction (cont.): Contingent weighting Distinction bias Lay rationalism Calculated risk/benefit tradeoffs?(almost never!)
Efforts to communicate risk/benefit information must address the challenges of preference construction There are no neutral frames for presenting information. Framing, response modes, and context all manipulate preferences. The concept of shared decision making needs rethinking. Whoever frames the decision problem manipulates the choice(inevitably!). See,e.g. Sunstein and Thaler s papers on Libertarian Paternalism.
There s more to the story: Enter Affect A valenced feeling (e.g., goodness or badness) associated with a stimulus Affect is one of many powerful elements in preference construction.
Four functions of affect 1. Acts as a common currency 2. Acts as information 3. Acts as a spotlight 4. Acts as a motivator of action (Peters, in press)
Trudeau s characters were really processing feelings associated with visual stimuli in what is known as the experiential mode of thinking.
There is no dearth of evidence in everyday life that people apprehend reality in two fundamentally different ways, one variously labeled intuitive, automatic, natural, non-verbal, narrative, and experiential, and the other analytical, deliberative, verbal, and rational. Seymour Epstein; 1994, p. 710
Two Modes of Thinking: Comparison of the Experiential and Analytic Systems Experiential System (System 1) Holistic Affective: pleasure-pain oriented Associationistic connections Behavior mediated by vibes from past experience Encodes reality in concrete images, metaphors and narratives More rapid processing: oriented towards immediate action Self-evidently valid: experiencing is believing Analytic System (System 2) Logical: reason oriented (what is sensible) Logical connections Behavior mediated by conscious appraisal of events Encodes reality in abstract symbols, words and numbers Slower processing: oriented towards delayed action Requires justification via logic and evidence Note: Adapted from Epstein, 1994
Valuation By Feelings Valuation By Calculation Reliance on Feelings Increases With: Innumeracy Cognitive Load complexity of task & information amount of information memory demands Stress time pressure pain poor health Older age Affect rich outcomes & images evaluable information displays
Risk As Analysis vs. Risk as Feelings Analytic/ Deliberative Experiential/ Affective
Reliance on feelings is sophisticated and essential to rational behavior but it can also get us into trouble.
High Risk Low Low Activities, hazards, etc. Benefit High In the world, risk and benefit are positively correlated. In people s minds, they are negatively correlated.
Risk High Activities, hazards, etc. Low Low Benefit High In people s minds,the correlation between risks and benefits is strongly negative!
The strength of the inverse (negative) relationship between risk and benefit judgments for a particular hazard (e.g. nuclear power) depends on the degree to which that hazardous activity is judged to be: good or bad.
5 4 3 2 1 5 4 3 2 1 Radiation Benefit Nuclear Power Chemicals Benefit Pesticides Risk Risk Benefit Risk X-rays Benefit Risk Prescription Drugs Figure 3. Mean perceived risk and perceived benefit for medical and nonmedical sources of exposure to radiation and chemicals. Each item was rated on a scale of perceived risk ranging from 1 (very low risk) to 7 (very high risk) and a scale of perceived benefit ranging from 1 (very low benefit) to 7 (very high benefit). Note that medical sources of exposure have more favorable benefit/risk ratings than do the nonmedical sources. Data are from a national survey in Canada by Slovic et al., 1991.
The Affect Heuristic How do I feel about a nuclear waste repository? +/ Perceived benefit Perceived risk A model of the affect heuristic explaining the risk/benefit confounding observed by Alhakami and Slovic (1994). Judgments of risk and benefit are assumed to be derived by reference to an overall affective evaluation of the stimulus item.
Benefit and Risk Perceptions Low Risk High Benefit Quadrant High Benefit High Risk High Benefit Quadrant High Risk Low Risk Low Benefit Quadrant High Risk Low Benefit Quadrant
Numeracy (from the cancer literature) The ability to understand and use basic probability and mathematical concepts (Lipkus et al., 2001)
Numeracy in UO undergraduate sample Table 1. Eleven items in the Numeracy Scale (Lipkus et al., 2001). Mean (median) score in UO undergraduate sample = 8.2 (8) out of 11 possible 1. 2. 3. 4. 5. 6. 7. 8/9. 10. 11. Items Imagine that we roll a fair, six-sided die 1,000 times. Out of 1,000 roles, how many times do you think the die would come up even (2, 4, or 6)? In the BIG BUCKS LOTTERY, the chances of winning a $10.00 prize are 1%. What is your best guess about how many people would win a $10.00 prize if 1,000 people each buy a single ticket from BIG BUCKS? In the ACME PUBLISHING SWEEPSTAKES, the chance of winning a car is 1 in 1,000. What percent of tickets of ACME PUBLISHING SWEEPSTAKES win a car? Which of the following numbers represents the biggest risk of getting a disease? 1 in 100, 1 in 1000, 1 in 10 Which of the following represents the biggest risk of getting a disease? 1%, 10%, 5% If Person A s risk of getting a disease is 1% in ten years, and Person B s risk is double that of A s, what is B s risk? If Person A s chance of getting a disease is 1 in 100 in ten years, and person B s risk is double that of A, what is B s risk? If the chance of getting a disease is 10%, how many people would be expected to get the disease out of 100?, out of 1000? If the chance of getting a disease is 20 out of 100, this would be the same as having a % chance of getting the disease. The chance of getting a viral infection is.0005. Out of 10,000 people, about how many of them are expected to get infected? % correct UO undergrads 61% 65% 42% 93% 95% 78% 70% 90%, 86% 85% 51% % correct older adults -- -- -- 76% 79% 66% 57% 72%, 67% -- --
Lower numeracy linked with: Lower comprehension Greater framing effects in decisions Greater influence of direct (and irrelevant) sources of affect and emotion in decisions Drawing less meaning from numbers Peters, Västfjäll, Slovic, Mertz, Mazzocco, & Dickert (in press) Psychological Science; Peters, Mazzocco, & Lipkus (in preparation); Peters, Dieckmann, & Mertz (in preparation)
Probability and Relative Frequency Are they the same or different in communicating risk? e.g., 1% chance vs. 1 out of 100
RISK COMMUNICATION: A patient Mr. James Jones has been evaluated for discharge from an acute civil mental health facility where he has been treated for the past several weeks. A psychologist whose professional opinion you respect has done a state-of-the-art assessment of Mr. Jones. Among the conclusions reached in the psychologist s assessment is the following: EITHER: Patients similar to Mr. Jones are estimated to have a 20% probability of committing an act of violence to others during the first several months after discharge. OR: Of every 100 patients similar to Mr. Jones, 20 are estimated to commit an act of violence to others during the first several months after discharge.
Question: If you were working as a supervisor at this mental health facility and received the psychologist s report, would you recommend that Mr. Jones be discharged from the hospital at the present time? 60% 40% 20% 0% 21% 20% probability 41% 20 of 100 patients Do not discharge
Patient Evaluation 10% Very few people are violent 10% = 1/10 Probably won t hurt anyone, though 1 out of 10 He could be the 1 out of 10 Some guy going crazy and killing people The patient attacking someone An act of violence There has to be at least 1 in 10. Mr. Jones could very well be that 1
New study High numerate hypothesized to have both formats accessible Probability condition Of every 100 patients similar to Mr. Jones, 10% are estimated to commit an act of violence to others during the first several months after discharge Frequency condition Of every 100 patients similar to Mr. Jones, 10 are estimated to commit an act of violence to others during the first several months after discharge
Perceived risk to others 5 Probability Frequency Perceived risk 2.5 3.9 3.7 3.8 1 Low numerate High numerate F(3,42)=4.4, p<.01 (Frame, p<.05; Numeracy, n.s.; Interaction, p<.05)
What do physicians say about drug risk/benefit communication and decision making? Some focus group comments consistent with the non-tradeoff,construction of preference,innumeracy story: *
my decision to put them on a particular drug would be based upon what I feel would have the lowest side effect profile and the easiest in terms of their compliance. That s basically where the risk/benefit ends. MD decides--searching for dominance structure
I will open the floor for discussion if they have any concerns about it or if they phone regarding some problems with the medication, but it s not high up there in my need for dialogue with the patient. low priority
people tend to either overestimate or underestimate risk so it s just difficult to communicate with somebody who believes that they can take this medication and not have any risk at all. No R/B tradeoff
if you say there s a one in a thousand chance of something happening to you, then people say, well statistics don t apply to me. I use the word risk umpteen times every day, and I find so often they really just can t understand what it is you re trying to convey. innumeracy *
When new drugs come out my practice is usually to avoid them unless the information says this is far superior to anything that s available. dominance seeking
I d say more of my older patients just will do whatever you tell them you think is best, and even sometimes when you try to have conversations about risks and benefits they ll just go,it doesn t matter, just tell me what you want me to do They re just sort of defaulting to what you think. trust, default to MD decision *
90% of the drugs that we prescribe are the same 20 drugs so usually we know everything about them backward and forward. The other 10% is what we have to kind of stop and scratch our head and think about. you tend to stick to the familiar Drugs work,md decides, low risk
many patients don t see some of those substances as being risky at all. No risk,no tradeoff
I mean you know, there are common side effects and uncommon side effects and it s usually when you present it to a patient that way they don t say well, what percentage of the time is it common and what percentage of the time it is uncommon. So that s the sort of language you use, common side effects and uncommon side effects. innumeracy
usually my conversations with patients don t revolve around statistics innumeracy?
statistics for the individual really are sort of meaningless. I mean, if they have a side effect it s 100% for them so really when we talk with patients about these things it s certainly not unusual for me to say, if you re noticing anything unusual call me. Information used primarily for monitoring
I had a patient today who stopped her birth control pill because her friend got a side effect from the same pill. No tradeoff
doctors are almost counselors.we cheerlead and we cajole and we try to charm them.that s what we do all day long. Nothing about risk/benefit discussions
Occasionally people do ask about statistics. They ll want to know what percentage of people have this side effect, but that s really uncommon. They want to know in general, is this going to make me feel worse than I feel now or am I going to feel better. No tradeoff
The arimodex seems to work a little bit better and the side effects are less. Most women will choose to take tamoxifen because it is less expensive. Prominence: cost most important:decision based on cost.
Interviewer: I may be incorrect on this but I read that tamoxifen has with it s use increased risk of some other kinds of problems. A: Uterine cancer and blood clots. Interviewer: So that really does pose kind of an issue of a trade off between different types of risks that I think would be very hard for a patient to wrestle with. How would that be presented or dealt with? A: It s just put out there and some women just ignore it, some women can assess all that and make a decision and some just freeze and can t move at all. Conflict leads to decision avoidance (see,e.g.luce,bettman,payne).
Conclusion Effective design,presentation,and utilization of pharmaceutical risk/benefit information needs to be informed by an understanding of the psychology of judgment and decision making.such understanding needs to come from research.