(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 Talya Miron-Shatz, PhD.9/16/2009

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? Talya Miron-Shatz, PhD.6/11/2009

Let’s talk about shopping Talya Miron-Shatz, PhD. What do people make of genetic testing

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. Talya Miron-Shatz, PhD. What do people make of genetic testing

Who should understand medical information? Or - what is shared decision making ?

paternalism shared decision making informed choice A conceptual framework 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, : p

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 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. Talya Miron-Shatz, PhD.What do people make of genetic testing

Bayesian Inference Talya Miron-Shatz, PhD.What do people make of genetic testing

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) Talya Miron-Shatz, PhD.What do people make of genetic testing

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? Talya Miron-Shatz, PhD.What do people make of genetic testing

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 = P(B│A) = P(B) X P(A│B) = X 0.5 = ? P(A) Talya Miron-Shatz, PhD.What do people make of genetic counseling

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 Talya Miron-Shatz, PhD.What do people make of genetic testing

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 Talya Miron-Shatz, PhD.What do people make of genetic testing

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. Talya Miron-Shatz, PhD.What do people make of genetic testing

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. ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●●●●●●●●●●○●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●● Talya Miron-Shatz, PhD.What do people make of genetic testing

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. Talya Miron-Shatz, PhD.What do people make of genetic testing

Presentation format affects giving the correct answer Talya Miron-Shatz, PhD.What do people make of genetic testing

Presentation format affects how the risk is perceived Talya Miron-Shatz, PhD.What do people make of genetic testing

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. Talya Miron-Shatz, PhD.What do people make of genetic testing

Genetic counselors are also affected by representation (Miron-Shatz, Hanoch, and Saphire-Bernstein, submitted) Talya Miron-Shatz, PhD.What do people make of genetic testing

And they need to actively make sense of numbers Talya Miron-Shatz, PhD.What do people make of genetic testing

Talya Miron-Shatz, PhD.What do people make of genetic testing

F rom 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% ( 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.” Talya Miron-Shatz, PhD.What do people make of genetic testing

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. Talya Miron-Shatz, PhD.What do people make of genetic testing

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. Talya Miron-Shatz, PhD.What do people make of genetic testing

Does numeracy help? Numeracy = the ability to deal with numbers and comprehend them. Talya Miron-Shatz, PhD.What do people make of genetic testing

Comprehension of risk Talya Miron-Shatz, PhD.What do people make of genetic testing

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). Talya Miron-Shatz, PhD.What do people make of genetic testing?

Would verbal expressions of probability help? II Not really… Expressions are non- complementary (Kerlitz & Budescu, 1993) Likely = 63%, and unlikely = 14%. Intermediate expressions fluctuate more than extreme ones. E.g., ‘probable’ vs. ‘always’ Talya Miron-Shatz, PhD.What do people make of genetic testing?

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. Talya Miron-Shatz, PhD.What do people expect of genetic testing

False beliefs and expectations from screening: Talya Miron-Shatz, PhD.What do people expect of testing

Worries about the screening Talya Miron-Shatz, PhD.When does this go wrong

Willingness to pay for screening Talya Miron-Shatz, PhD.When does this go wrong

Low numeracy individuals are Slightly older Less educated: 48% college, 27% grad school As wealthy as high numeracy participants However… Talya Miron-Shatz, PhD.Who gets hurt the most

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… Talya Miron-Shatz, PhD.Should we care

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

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

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

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? Talya Miron-Shatz, PhD.9/14/2015

(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 Talya Miron-Shatz, PhD.9/16/2009