Clinical Decision Making

Question 1

What is meant by medical error

Answer 1

An error is defined as the failure of a planned action to be completed as intended (i.e., error of execution) or the use of a wrong plan to achieve an aim (i.e., error of planning).

Question 2

Give some examples of medical error

Answer 2

E.g. incorrect diagnosis failure to employ indicated tests error in the performance of an operation, procedure, or test, error in the dose or method of using a drug.

Question 3

Describe the impact of medical error on mortality in the U.S

Answer 3

251k deaths in 2013
3rd biggest cause of death
However, we’re not even counting it, medical error is not recorded on death certificates.

Question 4

Describe the impact of medical error in the U.K

Answer 4

• It is estimated that medication errors have contributed to 12 000 deaths per year in the NHS • The wider problem of medication errors may contribute to an additional £0.75 billion–£1.5 billion in additional healthcare expenditure

Question 5

Describe a scenario where a medical error is committed

Answer 5

Mr WJ was diagnosed with acute lymphoblastic leukaemia in 1999 aged 15. • By June 2000, he was in remission, but still needed three-monthly injections of two chemotherapy drugs - Vincristine (IV) and Cytosine (IT). • On 4th January 2001, WJ was mistakenly given Vincristine intrathecally. He became slowly paralysed and almost a month later his parents agreed to turn off his life support machine. • Similar errors involving Vincristine had beenmade 14 times in Britain since 1985, 11 resulted in death the other 3 in paralysis. • The Specialist Registrar involved was convicted of manslaughter and sentenced to 8 months imprisonment.

Could be due to hierarchy and conformity.

Question 6

Describe the effect of extraneous factors on clinical-decision making

Answer 6

Junior-senior relationship may lead to the wrong decision being made
• Researchers placed a fictional drug in the ward drug cabinet. The label clearly stated: ‘Maximum Dose 10mg’ • ‘Dr Smith’ rang the ward and asked nurse to administer 20mg, and he would sign for it later • 21 out of 22 nurses prepared the dose

Question 7

Describe the different causes of medial error

Answer 7

Causes of medical error: almost 3/4 errors involve cognitive component  
No-fault: 7% 
System only: 18% 
Cognitive only: 28% 
Cognitive and system: 46%  

Need to address systems, but also our own cognition.

Question 8

Describe the costs of diagnostic errors in the U.S

Answer 8

A review of 25 years of U.S. malpractice claim payouts, found that diagnostic errors — not surgical mistakes or medication overdoses — accounted for: - the largest fraction of claims, - the most severe patient harm (Diagnostic errors more often resulted in death) - the highest total of penalty payouts • Diagnosis-related payments amounted to $38.8 billion between 1986 and 2010

Question 9

Describe the key features of clinical decision making

Answer 9

• Clinicians rarely use formal computations to make patient care decisions in day-to-day practice. • Intuitive understanding of probabilities is combined with cognitive processes called heuristics to guide clinical judgment. • Heuristics are often referred to as rules of thumb, educated guesses, or mental shortcuts. • Heuristics usually involve pattern recognition and rely on a subconscious integration of patient data with prior experience

Heuristics good in high pressure scenarios.

Question 10

Describe the ‘hot’ system for decision making

Answer 10

Emotional
'GO'
Simple
Reflexive
Fast
Develops Early
Accentuated by stress
Stimulus control

Question 11

Describe the ‘cold’ system for decision making

Answer 11

Cognitive 
'Know'
Develops late
Complex
Reflective
Slow
Develops Late
Attenuated by stress
Self control.

Question 12

Describe the dynamic relationship between the two different systems of decision making

Answer 12

When looking a illusions of lines that appear different lengths but are in fact the same length
Hot system initially tells us that they are different lengths
But the cold system soon kicks in to tell us that they are the same length.

Question 13

What did the Nisbett and WIlson study show about our potentially false belief that we are thinking rationally

Answer 13

An experimenter conducted a “consumer study” in a shopping mall. He laid out four pairs of tights in a row and asked consumers to pick out the pair they liked the best. In reality all four were identical. However, consumers were significantly more likely to select the far right most pair (even though they were switched around randomly each time).
Moreover when asked about their selection the consumers were able to provide justifications for their choice e.g. sheerness, strength etc. None mentioned the position, indeed when the experimenter suggested that position may have influenced their choice they looked at him as if he was mad!
System 1 (Hot) often controls our actions automatically but system 2 (Cold) is blissfully unaware, believing itself to be in charge! 

May be right-sided dominance.

Question 14

Define what is meant by confirmatory bias

Answer 14

• The tendency to search for or seek, interpret, and recall information in a way that confirms one’s preexisting beliefs or hypotheses, often leading to errors

Question 15

Describe the impact of confirmatory bias in medicine

Answer 15

Is confirmation bias to blame for the ineffective medical procedures that were used for centuries before the arrival of scientific medicine? - i.e leaching
• When evaluating a diagnosis be sure to test for alternatives

Question 16

Describe the potential issue of overconfidence in medicine

Answer 16

• Podbregar and colleagues studied 126 patients who died in the ICU and underwent autopsy • Physicians were asked to provide the clinical diagnosis and also their level of uncertainty • Clinicians who were “completely certain” of the diagnosis ante-mortem were wrong 40% of the time

May be adaptive- need to give yourself authority and trust in stressful environments.

Question 17

Describe the sunk cost fallacy

Answer 17

• Sunk costs are any costs that have been spent on a project that are irretrievable ranging including anything from money spent building a house to expensive drugs used to treat a patient with a rare disease.
• Rationally the only factor affecting future action should be the future costs/benefit ratio but humans do not always act rationally and often the more we have invested in the past the more we are prepared to invest in a problem in the future, this is known as the Sunk Cost Fallacy
Also called the ‘concorde effect’.

Question 18

Describe the Bornstein study showing the impact of the sunk cost fallacy in medical care

Answer 18

• Bornstein et al (1999) found that medical residents’ evaluation of treatment decisions were not influenced by the amount of time and/or money that had already been invested in treating a patient. • However, the residents did demonstrate a sunk-cost effect in evaluating non-medical situations

Question 19

What type of heuristic is anchoring

Answer 19

Anchoring and adjustment is a psychological heuristic that influences the way people intuitively assess probabilities. According to this heuristic, people start with an implicitly suggested reference point (the “anchor”) and make adjustments to it to reach their estimate.

Question 20

Describe what is meant by anchoring

Answer 20

Individuals poor at adjusting estimates from a given starting point (probs. & values)
• Adjustments crude & imprecise
• Anchored by starting point

Question 21

What does anchoring influence

Answer 21

– it influences the way people intuitively assess probabilities
In other words, it is a cognitive bias that describes the tendency to rely too heavily on the first piece of information offered when making decisions. Once the anchor is set, future decisions are made by adjusting away from that anchor

Question 22

Give a clinical example of the anchoring effect

Answer 22

• A working diagnosis of acute pancreatitis may seem quite reasonable in a 60-yr-old man who has epigastric pain and nausea, who is sitting forward clutching his abdomen • However, the patient states that he has had no alcohol in many years and investigations show normal blood levels of pancreatic enzymes • Clinicians may simply dismiss or excuse conflicting data (eg, the patient is lying, his pancreas is burned out, the laboratory made a mistake)

Question 23

Give an everyday example of the anchoring effect

Answer 23

§ Per this heuristic, people start with the implicitly suggested reference point (the “anchor”) and adjust it to reach their estimate (adjustments).
o I.E. A price of an item says “Reduced from £100 to £50” then we think this is a great deal (even if it’s not worth £50) as the anchor is £100.

Question 24

Describe the importance of probability in clinical practice

Answer 24

Many clinical situations involve making decisions on the basis of probabilities e.g. two or more competing diagnoses, alternative treatments which may be effective etc.

Question 25

What is meant by the representativeness heuristic

Answer 25

• Subjective probability that a stimulus belongs to a particular class based on how ‘typical’ of that class it appears to be (regardless of base rate probability)
• While often very useful in everyday life, it can also result in neglect of relevant base rates and other errors

Question 26

Give an example of a representativeness error in clinical practice

Answer 26

• A 60-yr-old woman who has no known medical problems and who now looks and feels well reports experiencing symptoms earlier of feeling short of breath, sweaty and clammy, feeling sick, and feeling faint. • This does not match the typical profile of an MI, which is typically characterised by chest pain. • BUT, it would be unwise to dismiss that possibility because MI is common among women of that age and has highly variable presentations.

Question 27

Define conditional probability

Answer 27

Measures the probability of an event happening given that another event has occurred

Question 28

What is Bayes’ theorem and what is it used for

Answer 28

It is a theorem that measures conditional probability

It is used in screening that involves false positives and false negatives such as mammograms/breast cancer

Question 29

Describe what is meant by the gambler’s fallacy

Answer 29

The gambler’s fallacy is a logical fallacy involving the mistaken belief that past events will affect future events when dealing with random activities, such as many gambling games.

Question 30

Describe the framing effect and age

Answer 30

• When presented with treatment descriptions described in positive, negative, or neutral terms, older adults are significantly more likely to agree to a treatment when it is positively described than they are to agree to the same treatment when it is described neutrally or negatively

Loss aversion- more people would rather avoid losing £5 than gaining the equivalent- important in public health messages and drug treatments offered

Question 31

Describe the role of the framing effect in medicine

Answer 31

• Patient choice: “Out of 100 patients taking this drug 70% get better”
vs
“Out of 100 patients taking this drug 30% don’t get better”

Question 32

What is meant by the availability heuristic

Answer 32

• Probabilities are estimated on the basis of how easily and/or vividly they can be called to mind. • Individuals typically overestimate the frequency of occurrence of catastrophic, dramatic events e.g. surveys show 80% believe that accidents cause more deaths than strokes • People tend to heavily weigh their judgments toward more recent information

Question 33

Describe availability errors in clinical practice

Answer 33

• For example, a clinician who recently missed the diagnosis of pulmonary embolism in a healthy young woman who had vague chest discomfort but no other findings or apparent risk factors might then overestimate the risk in similar patients and become more likely to do chest CT angiography for similar patients despite the very small probability of disease.

Question 34

Summarise the different ways in which we can improve clinical decision making

Answer 34

Recognize that heuristics and biases may be affectingour judgement even though we may not be conscious of them
Counteract the effect of top-down information processing by generating alternative theories and looking for evidence to support them rather than just looking for evidence which confirms our preferred theory.
Understand and employ statistical principles e.g. the law of large numbers i.e. the larger the sample size the greater your confidence can be in your judgements.
Use of Algorithms

Question 35

How can decision making be improved

Answer 35

1) Education and Training Integrate teaching about cognitive error and diagnostic error into medical school curricula Recognise that heuristics and biases may be affecting our judgement even though we may not be conscious of them
2) Feedback Increase number of autopsies Conduct regular and systematic audits Follow-up patients
3) Accountability Establish clear accountability and follow-up for decisions made
4) Generating alternatives Establish forced consideration of alternative possibilities e.g., the generation and working through of a differential diagnosis. Encourage routinely asking the question: What else might this be?
5) Consultation Seek second opinions Use of algorithms Use of clinical decision making support systems

Question 36

What is mean by an algorithm

Answer 36

An algorithm is a procedure which, if followed exactly, will provide the most likely answer based on the evidence.
• The rules of probability are examples of algorithms.
• Algorithms are most useful in situations where the problem is well defined - which excludes many everyday decisions
• For the most part, people have to be taught how to use them

Question 37

Describe the issues with the uses of algoritims in clinical practice

Answer 37

A logical series of steps to take in order to make a decision most effectively, but not necessarily most efficiently
May not take into account co-morbities and so may not be perfectly applicable to the presenting patient.

Question 38

Describe the future use of clinical decision making support systems

Answer 38

Used in conjunction with our cognition

Work with us to avoid errors- more of an inter-dependency.