Discussing numerical data with patients

Framing Framing manipulations: describing equivalent choice situations in different ways Information on relative risk is more persuasive than absolute risk data More information and more understandable information is associated with greater wariness to take treatments or tests 2

Framing “Loss” framing influences screening uptake more than “gain” framing (e.g. potential losses from not having a mammogram) Positive framing (e.g. chance of survival) is more effective than negative framing (chance of death) in persuading people to take risky options

How do patients perceive risk? How is this perception influenced by social context?

Patients’ understanding of risk Perceptions built up over time are informed by personal experiences, social networks shaped by behavioral norms and media reporting 9 Patients extract the gist of information, not detail, to make decisions 11

Social Context and Risk Perception 14 Social context of a disease (e.g. seizure, HIV) Perceived right to access or pursuit of equitability Trust in source of information Relation to other perceived risks Fit with previous knowledge and experience

For most, assessment of risk is guided by emotion, not facts 11 Avoidance of regret Personal level of risk aversion Short term gain may be valued over long term loss Fear difficulty and importance of decisions

Communicating Risk to Patients What methods enhance communication?

Avoid using only descriptive terms Large gap in perceived meanings of terms like “low risk” Difference can be up to an order of magnitude Try to be as specific as possible If you cannot use numbers try to use a standardized vocabulary E.g. Very common, common, uncommon, rare, very rare Best used alongside numbers DO EXERCISE

Use a consistent denominator & time frame Many patients have difficulty determining which risk is greater when options are presented with different denominators Instead of “1 in 25” vs “1 in 200” say “40 in 1000” vs “5 in 1000” Common denominators easier for people with less education to understand Use same denominator for benefits and harms However, denominators greater than 1000 are hard to understand 2

Offer positive and negative outcomes Do not present only the negative outcome “97 out of 100 people are cured” versus “3 out of 100 people die” produce very different perceptions of risk. Use both perspectives when possible to avoid influence of framing Make clear which outcome is better or worse (e.g. high versus low HDL) 7

Use absolute numbers (natural frequencies) Do not use relative risks, percentages, NNT, or conditional probabilities Reasoning improves dramatically when probabilities are converted into frequencies Even physicians do much worse with these 6 However, for rare occurrences natural frequencies may be hard to understand 2 Comparisons to common risks help Patients prefer relative risks, but do not understand them (neither do doctors)

Conditional Probabilities: Example 15 The probability that a woman has breast cancer is 0.8%. If she has breast cancer, the probability that a mammogram will show a positive result is 90%. If a woman does not have breast cancer the probability of a positive result is 7%. So, if you have a positive mammogram the probability that you have breast cancer is …

Natural Frequencies: Example 15 Eight out of every 1000 women have breast cancer. Of these eight women with breast cancer seven will have a positive result on mammography. Of the 992 women who do not have breast cancer 70 will still have a positive mammogram. So, if you have a positive mammogram…

Pictorial representations Use simple formats and absolute numbers Avoid using areas or volumes (eg pie charts) Log scales

Use visual aids for probabilities and partnership-building

Copyright ©2003 BMJ Publishing Group Ltd. Paling, J. BMJ 2003;327: Fig 4 Revised Paling Perspective Scale(C) --for displaying risks covering widely different orders of magnitude 16

Use comparisons for rare events Compare to everyday risks such as risk of death in a car crash 2

Avoid information overload “don’t dump: chunk” Limit information to necessary amount Get to the point Provide accurate summary of key points, including risks and benefits Be brief, but complete Present as simply as possible without distorting message 7