Tolerating Uncertainty In Medicine

Transcription

1 Tolerating Uncertainty In Medicine J. Panzer Kindercardiologie 2018 Universitair Ziekenhuis Gent 1

2 Medicine is not an Art and certainly not a Science Osler s maxim: medicine is a science of uncertainty and an art of probability Universitair Ziekenhuis Gent 2

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4 Too often, we focus on transforming a patient s gray-scale narrative into a black-and-white diagnosis that can be neatly categorized and labeled. The unintended consequence an obsession with finding the right answer, at the risk of oversimplifying the richly iterative and evolutionary nature of clinical reasoning is the very antithesis of humanistic, individualized patient-centered care Universitair Ziekenhuis Gent 4

5 Yet the reality is that doctors continually have to make decisions on the basis of imperfect data and limited knowledge, which leads to diagnostic uncertainty, coupled with the uncertainty that arises from unpredictable patient responses to treatment and from health care outcomes that are far from binary Universitair Ziekenhuis Gent 5

6 The Single 100% Correct Answer Dogma Most mathematical problems have one single correct answer. Medicine does not fit the traditional classical mathematical model and needs other models of logic to address the inherent uncertainty in medicine Universitair Ziekenhuis Gent 6

7 Logic in Medicine Classical logic assumes that each sentence is either true or false. But this standard creates a problem when describing ambiguous, inexact phenomena and formalising the intermediate situations. Temporal logic is used to describe any independent of each other systems which formalise expressions containing time phrases Fuzzy logic differ from the classical approach, which assumes that an item belongs to the set or not. Such classification is like the human process of thinking, reasoning and interpreting occurrence. There are concepts of half-truths, almost false and practically true and there are admissible logical values in the range [0,1] 2018 Universitair Ziekenhuis Gent 7

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9 medicine frequently involves making rapid decisions on the basis of a large and disparate array of information.this requires an intuitive, or non-explicit weighting of various factors. Fuzzy logic was introduced by Zadeh in the 1960s (8, 10 12) and fuzzy logic has a particular advantage in areas where precise mathematical description of the control process is impossible and is thus especially suited to support medical decision making Universitair Ziekenhuis Gent 9

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11 What is logic? What is fuzziness and what meaning has the term fuzzy logic? Medical fuzziness is impreciseness: a fuzzy proposition may be true in some degree. The word crisp is used as meaning nonfuzzy. An example of fuzzy propositions is the patient is young and is true in some degree, the lower the age the more the truth. Truth of a fuzzy proposition is a matter of degree Universitair Ziekenhuis Gent 11

12 The spectrum of Health or Disease -A Patient is never 100% healthy or 100% ill (unless dead). Eg: A patient might be very healthy but have acne. He/She might consider themselves to be very healthy to very ill (subjective) and the physician might consider him/her very healthy or very ill (subjective mixed with objective criteria) Leading to differences in QOL perception Universitair Ziekenhuis Gent 12

13 Spectrum of Disease, Tetralogy of Fallot Spectrum from VSD to PA,VSD pathophysiologically VSD: L-R overshunting:?diuretics From L-R to R-L PA: R-L increasing cyanosis:?shunt Classical logic ToF therefore Rx. Temporal Logic With time shift in pathophysiology Fuzzy Logic Fluid hypothesis/diagnosis between extremes, Changing in time This is an example of why we need physicians as we are much better than computers at integrating all information into a working and changing hypothesis to tailor our Rx! 2018 Universitair Ziekenhuis Gent 13

14 Current Working Hypothesis rather than a Diagnosis Spectrum 0-1, where does my patient currently fall..? 2018 Universitair Ziekenhuis Gent 14

15 Thinking Errors Survivorship Bias Swimmers Body Illusion Overconfidence-Effect Social Proof Sunk Cost Fallacy Confirmation Bias Authority Bias Contrasteffect Availability Bias Story Bias Retrospective Bias Control illusion Outcome Bias Selection Paradox Liking Bias Endowment effect The miracle Groupthink Neglect of probability Zero-risk bias Beauty Bias Social Loafing Winner s curse Wrong causality Prognosis illusion Framing Action Bias Omission Bias Self-Serving Bias Hedonic treadmill Self-selection bias Association bias Beginners luck Hyperbolic discounting 2018 Universitair Ziekenhuis Gent 15

16 Examples of frequent Thinking Errors Phycians make - We tend to believe what we don t understand. - We tend to think of a diagnosis as an absolute certainty.. - We tend to believe those in authority even if they don t have any particular expertise in this problem. - The repetitive diagnosis leads to everything has to fit in this box even if it doesn t.. - We tend to want to explain all symptoms/findings by our one diagnosis even if they don t fit - We tend to stop thinking if someone else knows more about this subject and tells as what to do 2018 Universitair Ziekenhuis Gent 16

17 How to address uncertainty 1. Be aware of uncertainty 2. Gather as much evidence as possible from various sources 3. Try to understand the process (pathophysiology) 4. Remain open to an initial wrong diagnosis or changing diagnosis 5. Be aware of common thinking errors 6. Communicate uncertainty in understandable language to the patient and have the patient participate in decision making. 7. Do your fellow physicians a favour: don t trust them! 2018 Universitair Ziekenhuis Gent 17

18 Case 1 Neonate day 5 diagnosed with murmur by Paediatrician in a regional hospital. Echocardiography Cardiologist normal. Follow-up 4 years with innocent murmur only to be finally diagnosed with VSD and PHT leading to death at 4 years of age Universitair Ziekenhuis Gent 18

19 Case 1 reflections 1. Be aware of uncertainty Were the Physicians? Initial uncertainty was intolerable and led to an echo, thereafter there was no more uncertainty. 2. Gather as much evidence as possible from various sources Clinical Examination, growth, second opinion? 3. Remain open to an initial wrong diagnosis or changing diagnosis Were the Physicians aware of the possibility of a wrong hypothesis? 4. Be aware of common thinking errors We tend to believe the result of an examination we can t perform ourselves or don t understand. 5. Communicate uncertainty in understandable language to the patient Uncertainty was never communicated to the patient which led to shock and anger when the diagnosis changed later 2018 Universitair Ziekenhuis Gent 19

20 Case 2 Neonate with diagnosed tetralogy of Fallot develops low saturation of 60% on the neonatal unit. Nursing staff and attending medical staff accept this situation in the light of the cyanotic heart lesion. After a few hours further desaturation to 40% with increased resp. difficulty with the diagnosis of a pneumothorax Universitair Ziekenhuis Gent 20

21 Case 2 reflections 1. Be aware of uncertainty of the cause of the desaturation (and the diagnosis of tetralogy of Fallot)? 2. Gather as much evidence as possible from various sources Clinical Examination, CXR? 3. Remain open to an initial wrong diagnosis or changing diagnosis Double pathology? 4. Be aware of common thinking errors All findings have to fit into the box of the original diagnosis. 5. Communicate uncertainty in understandable language to the patient 2018 Universitair Ziekenhuis Gent 21

22 Case 3 12 yr old child followed after UTI with hypertension Finally diagnosed with coarctation of the aorta Universitair Ziekenhuis Gent 22

23 Case 3 reflections 1. Be aware of uncertainty of the cause of the hypertension 2. Gather as much evidence as possible from various sources Clinical Examination? 3. Remain open to an initial wrong diagnosis or changing diagnosis Double pathology or other cause of hypertension and no renal damage from UTI? 4. Be aware of common thinking errors All findings have to fit into the box of the original diagnosis. After the diagnosis has been made we make no effort to eliminate other causes of hypertension. 5. Communicate uncertainty in understandable language to the patient Patients are usually (rightly) upset when the diagnosis changes or uncertainty becomes apparent if we have always made a show of certainty 2018 Universitair Ziekenhuis Gent 23

24 Case 4 10 yr old Boy admitted with anorexia and abdominal pain and rather poorly. (4 other children admitted the same day with gastroenteritis) After IV fluid bolus he deteriorated and needed intubation. The diagnosis of biventricular heart failure was finally made Universitair Ziekenhuis Gent 24

25 Case 4 reflections 1. Be aware of uncertainty of the cause of abdominal pain 2. Gather as much evidence as possible from various sources Cardiac Clinical Examination? 3. Remain open to an initial wrong diagnosis or changing diagnosis Double pathology or other cause of anorexia and abdominal pain? 4. Be aware of common thinking errors Repetitive Diagnosis error 5. Communicate uncertainty in understandable language to the patient Patients are usually (rightly) upset when the diagnosis changes or uncertainty becomes apparent if we have always made a show of certainty 2018 Universitair Ziekenhuis Gent 25

26 Case 5 15 yr old boy with DCM after art switch procedure is unwell with reduced exercise tolerance but only when a wind blows from NW according to mother. Admitted, Cath: LV failure with low-moderate PHT. Parents don t want a heart transplant because 1. He ll need to take a lot of medicine and 2. He ll have reduced exercise tolerance Universitair Ziekenhuis Gent 26

27 Case 5 reflections 1. Be aware of uncertainty of the outcome regardless of options! Uncertainty of clinical complaints/ Münchhausen by proxy 2. Gather as much evidence as possible from various sources Admission and full work-up including cath? 3. Remain open to an initial wrong diagnosis or changing diagnosis Cause of current complaints? 4. Be aware of common thinking errors The mother does have weird ideas but he is ill as well. 5. Communicate uncertainty in understandable language to the patient Parents informed that he has reduced exercise capacity already anyway and is already taking a lot of medicine anyway: Heart transplant candidate BUT transition to a (female) adult cardiologist Parents don t come for follow-up regularly anymore and when they return he has irreversible PHT and dies at age 17yr Universitair Ziekenhuis Gent 27

28 Case 6 2 yr old boy has fever for a few days and a cardiac murmur. Previously diagnosed with an innocent murmur. Treated a few days with ABs before transferring to UZGent. Diagnosis Infective endocarditis of mitral valve with mitral valve insufficiency Universitair Ziekenhuis Gent 28

29 Case 6 reflections 1. Be aware of uncertainty of the cause of the murmur 2. Gather as much evidence as possible from various sources Clinical Examination: holosystolic murmur over the apex? 3. Remain open to an initial wrong diagnosis or changing diagnosis Cause of murmur? 4. Be aware of common thinking errors The previous echo remains valid for the rest of his life? 5. Communicate uncertainty in understandable language to the patient Parents should have been informed that the working hypothesis could change as information changes Universitair Ziekenhuis Gent 29

30 medicine is a science of uncertainty and an art of probability. And that s what makes us better than computers and keeps things interesting! 2018 Universitair Ziekenhuis Gent 30