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(Mis)understanding medical information: healthcare professionals and laymen alike Talya Miron-Shatz, Ph.D. Center for Health and Wellbeing Princeton University Talk at the School of Public Affairs, Baruch College 9/16/2009 Talya Miron-Shatz, PhD. Agenda Who should understand medical information? What do people make of genetic testing? What do they expect of testing? When does this go wrong? Who gets hurt the most? Should we care? 6/11/2009 Talya Miron-Shatz, PhD. Let’s talk about shopping What do people make of genetic testing Talya Miron-Shatz, PhD. Meaning and value are actively inferred We – you, me, everybody – base our judgment and evaluation of alternatives on the way in which they are represented to us. This is because humans are wired to save cognitive effort. By acknowledging this, one can influence (bias) behavior. What do people make of genetic testing Talya Miron-Shatz, PhD. Who should understand medical information? Or what is shared decision making ? A conceptual framework paternalism shared decision making informed choice Depends on the patient-clinician interaction, plus other elements Charles C, Gafni A, and Whelan T, Shared decision-making in the medical encounter: what does it mean? (Or it takes at least two to tango). Soc Sci Med, 1997. 44: p. 681-92. Shared Decision Making Shared decision making involves at least two (often many more) participants—the health professional and the patient Both parties take steps to participate in the process Information sharing is a prerequisite Information is needed about both ‘risks’ and ‘values’ A decision is made or deferred Shared decision making: skills Problem definition Portray equipoise Portray options Check understanding Explore ideas, concerns, expectations Role preference Decision making Deferment if necessary Review arrangements Elwyn, 2001 Shared decision making ‘Involving the patient in the decision making, to the extent that they desire’ Key skills or ‘competences’ Do patients want to be involved in decisions ? Who should make treatment decisions? Picker Europe Survey 8000 patients, 8 countries, Jul 2002 60 50 40 30 20 Doctor Doctor and patient together Patient 10 0 Coulter A and Magee H, eds. The European patient of the future. 2003, Open University Press: Maidenhead. “There is a 30% chance of rain tomorrow.” (Gigerenzer et al.) 1. It will rain in 30% of the area. 2. It will rain for 30% of the time. 3. On 30% of days like this it rains. What do people make of genetic testing Talya Miron-Shatz, PhD. Bayesian Inference What do people make of genetic testing Talya Miron-Shatz, PhD. P(A|B) is NOT p (B|A) A = The effect (genotype), what we see B = What we are seeking (disease, phenotype) P(B│A) = P(B) X P(A│B) P(A) What do people make of genetic testing Talya Miron-Shatz, PhD. A relatively simple scenario… The probability of colon cancer is 0.3% If a person has colon cancer, the probability of a positive test result is 50% If a person does not have colon cancer, the probability of a positive test result is 3% What is the probability that a person has colon cancer, if he tests positive? What do people make of genetic testing Talya Miron-Shatz, PhD. If you test positive for colon cancer, do you have it? P(A) = p(A|B) + p (A|B’) P(A|B) = .5 p (A|B’) = 0.03 X 0.997 = 0.02991 P(B│A) = P(B) X P(A│B) = 0.003 X 0.5 P(A) 0.02991 What do people make of genetic counseling Talya Miron-Shatz, PhD. =? Rephrasing as Natural Frequency Out of every 10,000 people, 30 will have colon cancer. Out of these people, 15 will test positive. Out of the remaining 9,970 people, 300 will test positive. How many of the people who test positive have colon cancer? What do people make of genetic testing Talya Miron-Shatz, PhD. Results from a current study (Miron-Shatz, Hanoch, Graef & Sagi, forthcoming, J. of Health Communication) 264 Princeton students participated in an online survey about genetic screening Students read a hypothetical letter to an expectant mother who had an elevated risk of having a baby with Down syndrome Probabilistic Frequentist Visual What do people make of genetic testing Talya Miron-Shatz, PhD. Probabilistic presentation The probability of giving birth to a baby with Down syndrome for a woman with normal results is 1:724 The probability of giving birth to a baby with Down syndrome for a woman with your abnormal result is 1:181 What do people make of genetic testing Talya Miron-Shatz, PhD. Frequentist presentation One out of every 724 fetuses of women your age will be diagnosed with Down syndrome. One out of every 181 fetuses of women your age with screening results that are identical to yours will be diagnosed with Down syndrome. What do people make of genetic testing Talya Miron-Shatz, PhD. Visual presentation The white circle in the picture represents the only fetus with Down syndrome out of all the fetuses of women your age who have not yet been screened. There are 724 circles in the picture. ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●●●●●●●●●●○●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●● What do people make of genetic testing Talya Miron-Shatz, PhD. Visual presentation The white circle in the picture represents the only fetus with Down syndrome out of all the fetuses of women whose screening results were identical to yours. There are 181 circles. What do people make of genetic testing Talya Miron-Shatz, PhD. Percent correct answer Presentation format affects giving the correct answer 70 60 50 40 30 20 10 0 probability visual Presentation form What do people make of genetic testing Talya Miron-Shatz, PhD. frequency PErcentages risk evaluations Presentation format affects how the risk is perceived 70 60 50 don't know 40 low 30 medium 20 high 10 0 probability frequency Presentation form What do people make of genetic testing Talya Miron-Shatz, PhD. visual In your opinion, how clear will it be for a woman who received the letter whether a 1:181 chance of having a fetus with Down Syndrome is good or bad? The probabilistic and frequentist presentations are perceived as equally clear. What do people make of genetic testing Talya Miron-Shatz, PhD. Genetic counselors are also affected by representation (Miron-Shatz, Hanoch, and Saphire-Bernstein, submitted) 100.0% 90.0% 80.0% 70.0% 60.0% Probabilistic 50.0% Frequentist 40.0% 30.0% 20.0% 10.0% 0.0% Probability - 0-20% Risk - Low or Medium Probability - Correct Horse Disease What do people make of genetic testing Risk - Low or Medium Ear Problem Talya Miron-Shatz, PhD. And they need to actively make sense of numbers What do people make of genetic testing Talya Miron-Shatz, PhD. What do people make of genetic testing Talya Miron-Shatz, PhD. From the official National Cancer Institute (NCI) website “According to estimates of lifetime risk, about 13.2% (132 out of 1,000 individuals) of women in the general population will develop breast cancer, compared with estimates of 36 to 85% (360-850 out of 1000) of women with an altered BRCA1 or BRCA2 gene. In other words, women with an altered BRCA1 or BRCA2 gene are 3 to 7 times more likely to develop breast cancer than women without alterations in those genes.” What do people make of genetic testing Talya Miron-Shatz, PhD. I Breast cancer will develop in all women age 36 to 85. II Breast cancer will develop in 36 to 85 percent of women who are found to have BRCA1 and BRCA2 alterations. III Women who have BRCA1 and BRCA2 alterations will exhibit 36 to 85 percent of the symptoms associated with breast cancer. IV Women who are found to have alterations in the genes called BRCA1 and BRCA2 have 36% to 85% higher chance of developing breast cancer. What do people make of genetic testing Talya Miron-Shatz, PhD. Lifetime risk of breast cancer (Hanoch & Miron-Shatz, submitted) An online survey, 284 women 47.5% chose the correct interpretation. 46.1% chose option iv, associating alterations in the BRCA1/2 genes with a 36% to 85% higher chance of developing breast cancer. What do people make of genetic testing Talya Miron-Shatz, PhD. Does numeracy help? Numeracy = the ability to deal with numbers and comprehend them. What do people make of genetic testing Talya Miron-Shatz, PhD. Comprehension of risk 70 60 Percentage 50 40 Low Numeracy (scored 0-8) High Numeracy (scored 9-11) 30 20 10 0 Most appropriate correct What do people make of genetic testing Numeric risk correct Talya Miron-Shatz, PhD. Would verbal expressions of probability help? I Not really… The ranking for various expressions is more or less constant, but the meaning differs according to context. ‘Rare side effects’ mean 1/1000 for using beta blockers, and 1/5 for antihistamines. (Kong et al, 1986, NEJM). What do people make of genetic testing? Talya Miron-Shatz, PhD. Would verbal expressions of probability help? II Not really… Expressions are noncomplementary (Kerlitz & Budescu, 1993) Likely = 63%, and unlikely = 14%. Intermediate expressions fluctuate more than extreme ones. E.g., ‘probable’ vs. ‘always’ What do people make of genetic testing? Talya Miron-Shatz, PhD. Importance of aspects of BRCA screening test (Miron-Shatz & Diefenbach) Give me information about my BRCA1 and BRCA2 status: 76% very important. Tell me with certainty whether I will develop breast cancer: 32% very important. * Tell me what to do in case I have breast cancer 34% very important. * * 50% the test cannot do that. What do people expect of genetic testing Talya Miron-Shatz, PhD. False beliefs and expectations from screening: 70 60 Percentage 50 40 Low Numeracy (scored 0-8) High Numeracy (scored 9-11) 30 20 10 0 Absolute risk What to do Participants who correctly responded: The test cannot do that What do people expect of testing Talya Miron-Shatz, PhD. Worries about the screening 3 Mean worry 2.5 2 1.5 1 0.5 0 Low Numeracy (scored 0-8) When does this go wrong Talya Miron-Shatz, PhD. High Numeracy (scored 9-11) Willingness to pay for screening 300 Willingess to pay in USD 250 200 150 100 50 0 Low Numeracy (scored 0-8) When does this go wrong Talya Miron-Shatz, PhD. High Numeracy (scored 9-11) Low numeracy individuals are Slightly older Less educated: 48% college, 27% grad school As wealthy as high numeracy participants However… Who gets hurt the most Talya Miron-Shatz, PhD. Do patients understand what we are talking about? A recent review (Elwyn et al.) found that counselors seldom ask about comprehension. Some patients think genes are – in your brain… in your knees… Should we care Talya Miron-Shatz, PhD. Conclusions Due to the nature of human cognition, presentation of information matters: Framing affects desirability of alternatives. The frequentist form is associated with better understanding than the probabilistic form. To facilitate understanding, whoever communicates information should acknowledge this. To conclude… [email protected] Clinical implications Even seemingly ‘neutral’ or ‘objective’ presentations of information carry emotional and cognitive implications. Frequentist representation facilitates the understanding of probabilistic information. We cannot assume comprehension. To conclude… [email protected] Implications for training Presenting information is a learned skill. The psychological aspects of decision making should be incorporated into medical and genetic counseling training programs. To conclude… [email protected] What we learned thus far What do people make of genetic testing? What do they expect of testing? When does this go wrong? Who gets hurt the most? Should we care? 7/18/2015 Talya Miron-Shatz, PhD. (Mis)understanding medical information: healthcare professionals and laymen alike Talya Miron-Shatz, Ph.D. Center for Health and Wellbeing Princeton University Talk at the School of Public Affairs, Baruch College 9/16/2009 Talya Miron-Shatz, PhD.