The status of heuristics and cognitive biases as a source of diagnostic errors.

Mark Graber Mark.Graber at IMPROVEDIAGNOSIS.ORG
Sat Nov 11 19:58:35 UTC 2017


As many of you know, I’m a big fan of the ‘stop and think’ approach to improve diagnosis, but in defense of System 1 let me offer you 2 interesting quotes:
Mark

“It is a profoundly erroneous truism, repeated by all copy-books and by eminent people making speeches, that we should cultivate the habit of thinking about what we are doing. The precise opposite is the case. Civilization advances by extending the number of operations which we can perform without thinking about them. Operations of thought are like cavalry charges in a battle -- they are strictly limited in number, they require fresh horses, and must only be made at decisive moments.”
A.N. Whitehead, 1911 (in J Bargh, 1999)

“others are surprised by how quickly I make big decisions, but I’ve learned to trust my instincts….The day I realized it was smart to be shallow was, for me, a deep experience.”   Donald Trump.  Quoted in the New Yorker  Sept 26 2016: Evan Osnos  “President Trump”


From: Pat Croskerry <croskerry at EASTLINK.CA>
Reply-To: Listserv ImproveDx <IMPROVEDX at LIST.IMPROVEDIAGNOSIS.ORG>, Pat Croskerry <croskerry at EASTLINK.CA>
Date: Saturday, November 11, 2017 at 11:17 AM
To: Listserv ImproveDx <IMPROVEDX at LIST.IMPROVEDIAGNOSIS.ORG>
Subject: Re: [IMPROVEDX] The status of heuristics and cognitive biases as a source of diagnostic errors.

Good discussion. I  want to pick up on one of  the points  made about heuristics and the tendency to call them biases when they fail.
We can maybe simplify the discussion by emphasising that, as has been noted here,  heuristics are inherent in human decision making, and it is virtually impossible not to engage them at some point in the decision making process – unless someone was working in a situation where there was little room for any error e.g. a space station. It is hard not to find something good to say about any particular heuristic, and in this more relaxed setting on Earth, we cannot function without them.  Anything that is abbreviated, fast, and frugal, by definition, is incomplete and will predictably fail at some point, so we are all vulnerable to heuristic failure. The essence of good decision making is to monitor the output from System 1 – we need to be ever-vigilant in this, and recognise that it isn’t so much that the heuristic becomes a bias when it fails, instead, what has failed is our monitoring (astronauts have commented on the tedium of relentlessly checking, and re-checking everything in space). Metacognition, reflection and mindfulness are the terms used to describe monitoring – these processes are learnable and coachable, and should be part of our armamentarium in training clinical decision making.
Some people seem to have difficulty with the term ‘bias’ including those who deny outright that diagnostic failure may be due to bias – perhaps they might more readily accept things if the event was characterized as ‘heuristic failure’. An alternative terminological strategy was used some time ago when we tried to get over the negative connotation of the word ‘bias’ by calling it ‘disposition to respond’ , again, expecting that it might be easier to accept that dispositions to respond are vulnerable to failure. Whatever we call them, they are abundant in all walks of life.
Pat




From: Linda M. Isbell [mailto:lisbell at PSYCH.UMASS.EDU]
Sent: November 11, 2017 10:49 AM
To: IMPROVEDX at LIST.IMPROVEDIAGNOSIS.ORG
Subject: Re: [IMPROVEDX] The status of heuristics and cognitive biases as a source of diagnostic errors.


Thank you for your very thoughtful response to my earlier comment.  I too understand both sides of this situation, as well as the confusion inherent in discussions of heuristics and their value.  As a social psychologist, I would never say that heuristics are not VERY valuable - they are - they do lead us to navigate our worlds with great success most of the time.  If we didn't have heuristics, or somehow found a way to eliminate them (impossible), we'd all screw up decision making far more often than we do now!!  As one famous social psychologist said long ago about the use of categories - "orderly living depends upon it."  Indeed, this is very ture.   So heuristics (and use of categories, for example, as one type of heuristic) are NOT inherently bad - generally the opposite is true.  Certainly the use of pattern-matching and other strategies of this sort lead to considerable diagnostic success oftentimes.  We certainly wouldn't want to intervene here.   The problem, however, is that sometimes (and by that I mean FAR more often than we could possibly realize), we SYSTEMATICALLY use heuristics in ways that are harmful and do lead to diagnostic failure and failures in all sorts of decisions.  We are often quite unaware of this.  Consider the problem of health care disparities, which are a significant problem in medicine (and diagnosis) - and other spheres of life.  People who present with physical health concerns and happen to have a comorbid mental illness, for example, are more likely to be misdiagnosed, undertreated, mistreated, ignored, etc.  We see disparities for race as well.  Why is this happening?  I am sure we can generate many possibilities (and of course it is an empirical question that some have already addressed in the literature), but one that is important and impossible to ignore is the fact that people (including health care providers) have stereotypes about different groups and apply these when making decisions.  Applying a stereotype (which is a type of heuristic) can lead to very bad outcomes.  Indeed their are some very noteworthy mortality gaps between different groups in society, with those that are the targets of stereotypes faring far worse than those who are not.  The problem then, is NOT that heuristics are bad, it is that heuristics are sometimes SYSTEMATICALLY applied in ways that are detrimental.  The "solution" then is to identify empirically when heuristics are being used in systematically problematic ways, which lead to systematically bad outcomes, and design interventions to remedy this particularly problematic application of heuristics.  This can be done, this should be done, and I am working on research on this issue.

In the end, I think we all know and accept that many things contribute to diagnostic error.  Of course lack of knowledge, experience, etc. are notable contributors (but they are also relatively easy to fix it seems compared to some others).  But so too is the systematic application of heuristics that systematically lead to errors.  In the absence of evidence that something systematic is happening, I would agree that it may be hard to intervene to reduce diagnostic errors in a highly significant way.  However, we know that something systematic is happening with some patient populations for sure, and for these patient populations, the misapplication of heuristics (e.g., stereotypes as one example) is contributing to a significant mortality gap, which has widespread health implications.

So, I think we likely agree more than we disagree.  And I think it is perhaps more semantic than some people might think.  Mostly, I think, discussions around the disadvantages and advantages of heuristics in any decision making requires that we contextualize the conditions we are talking about carefully.  Social cognitive processes aren't inherently good or bad - most social cognitive processes have evolved BECAUSE they are adaptive - the goal is to find out the conditions under which different processes lead to good versus bad decisions, and attempt to intervene where necessary to improve the outcomes.

Best,

Linda


---
Linda M. Isbell, Ph.D.
Professor, Psychology
Department of Psychological and Brain Sciences
University of Massachusetts
135 Hicks Way -- 630 Tobin Hall
Amherst, Massachusetts 01003
Office Phone:  413-545-5960
Website:  http://people.umass.edu/lisbell/

On 2017-11-09 13:57, Shojania, Dr. Kaveh wrote:
I can see both sides of this debate/discussion.

I think one of the reasons for questioning the importance of heuristics as a cause of diagnostic errors is not the issue of frequency. It's more the following: heuristics are so often associated with diagnostic successes, that it's hard to argue they are the major problem.

If something (in this case,  set of heuristics) works 95% of the time, then it's hard to say it's a problem. or, rather, it's hard to argue that it should be abandoned

The vast majority of diagnoses are correctly made within less than a minute. That's a combination of pattern recognition and 'common things being common'.

So, to say that heuristics are to blame for most/many diagnostic errors doesn't really make sense, since they are reasonable for most diagnostic successes.

It doesn't help that the same behavior will be called diagnostic acuity when it's correct and a cog bias when it is not – in other words, it is not really possible to distinguish diagnostic acumen from diagnostic bias until the outcome is known, which means it's not that helpful of a concept in terms of preventing errors.

Except that, if one does want to reduce diagnostic errors, one needs to do something. And, that something is not so much to get rid of heuristics it is to recognize when one needs to shift to more deliberate and systematic thinking.

Sometimes that can happen during the first encounter with a patient – the patient says something or the doctor notices something that doesn't fit the pattern. The good diagnostician is not the person who avoids heuristics, but the one who listens to the little voice in their head saying 'Something's not quite right - time to step back and think about this more'

This is what many say about System I vs System Ii , thinking fast, thinking slow, etc

So, I am not saying anything original here. I am just pointing out that it maybe it's a semantic point. But, I think it is a bit more than that.

We have a situation that heuristics turn up frequently both in cases that do involve errors in diagnosis  and ones that do not.

From an epidemiologic point of view, that usually means that heuristics can't be a major cause of error. That's why we do case control studies – if the exposure turns up as often among cases as among controls, it's not a risk factor for the disease of interest.

This happens a lot in patient safety. One does a root cause analysis of a critical incident and identifies that the resident on the team was new that day, there was a temp nurse from an agency, the patient didn't speak English etc etc

It's tempting to jump on each of these as important causes of whatever bad thing happened.  The problem is that these same factors are present in so many other cases where nothing went wrong. The reality is that each of these factors may well play a small contributory  role. From a logical point of view, though, it's still hard to argue that X commonly causes Y, when X is commonly present in so many cases of Not Y. And, from a practical point of view, when X leads to a desirable outcome most of the time, why not do it and just get better at recognizing when that's not working? (In practice, we get good not just at recognizing when it is not working out now, but recognizing critical situation where the patient would suffer a bad outcome before we have time to shift our thinking. Eg, , that's why one constructs a differential diagnosis when seeing an cutely unwell patient – because one doesn't want the patient to suffer a bad outcome before one realizes the need to shift out of heuristic mode.)


-kgs




Kaveh G. Shojania, MD
Professor and Vice Chair, Quality & Innovation
Department of Medicine
Director, University of Toronto
Centre for Quality Improvement and Patient Safety (www.cquips.ca<http://www.cquips.ca/>)

Sunnybrook Health Sciences Centre
Room H468, 2075 Bayview Avenue
Toronto, Ontario M4N 3M5

Editor-in-chief, BMJ Quality & Safety

From: Grubenhoff, Joe [mailto:Joe.Grubenhoff at CHILDRENSCOLORADO.ORG]
Sent: Thursday, November 09, 2017 1:17 AM
To: IMPROVEDX at LIST.IMPROVEDIAGNOSIS.ORG<mailto:IMPROVEDX at LIST.IMPROVEDIAGNOSIS.ORG>
Subject: Re: [IMPROVEDX] The status of heuristics and cognitive biases as a source of diagnostic errors.

I too share a Dr. Isbell's reluctance to claim that heuristics are not a significant source of diagnostic error.

Having read Thinking Fast and Slow, I think that Kahneman and Tversky point out not that heuristics represent faulty probabilistic reasoning but rather a complete disregard of probabilities.

In the Linda experiment, the subject is provided a series of data points that are not necessarily predictive of her likelihood of being a feminist  but the subject draws inferences that provide cognitive coherence which make the less probable (statistically speaking) combination of being a feminist and a bank teller seem more likely than simply being a bank teller (all feminist bank tellers are wholly contained within the larger population of bank tellers).

In contrast, the "analogous" experiment contains faulty logic. A man presenting with a case description consistent with a PE may also have a UTI but the probability that he has a UTI in the absence of any signs/symptoms or data predictive of a UTI is highly unlikely. Further, the Venn diagram for the populations of patients with UTI and with PE overlap but one does not wholly contain the other except in very unique circumstances. To put it differently, the prevalence of UTI and PE can be known as, theoretically, could the presence of both existing together. But it cannot be taken as given that in all circumstances one group wholly contains the other. Contrast this with Liinda: ALL cases of feminist bank tellers must be contained within the group "bank tellers." I think most physicians would say that, in the absence of a more reasonable alternative answer (Jim has only a PE), they would be forced to choose "Jim has a UTI and PE" but would scratch their heads as to why those were the only two answers provided as they are implausible.

Work by Frank Papa suggests that representativeness IS very likely a key component of arriving at a correct diagnosis. Cases with a more typical presentation (e.g. AMI) are more likely to be correctly diagnosed than cases in which the features are atypical.

I don't understand this sentence: We note we do not need to invoke the heuristic of representativeness as an explanation for answer (a) because probabilistic reasoning has not been employed in this instance.

If the theoretical clinician choosing between answer (a) and (b) is not using representativeness (a heuristic strategy) and not using probabilistic reasoning, then how does she arrive at choosing (a) over (b). It seems the clinician choosing (a) is indeed using heuristics because she would have to ignore the improbable scenario in which Jim has a completely asymptomatic UTI in the presence of a PE (or alternatively, the clinical vignette is purposefully deceptive by leaving out any information about a UTI dx which is not reflective of actual practice).

The proposition that the solution to avoiding diagnostic errors requires "extensive knowledge and experience of diseases" ignores the finite capacity of the human mind and suggests the an approach to diagnosis that Marewski and Gigerenzer (Heuristic decision making in medicine - Marewski and Gigerenzer Dialogues in Clinical Neuroscience - Vol 14 . No. 1 . 2012) might call unbounded rationality. This is not an efficient (or even possible) strategy especially in light of the fact that the pre-test probabilities of many diseases based solely on history and exam findings are unknown and, at least in pediatrics, we have very few good screening and confirmatory tests for the conditions we encounter.

Lastly, while admittedly anecdotal, argues the point the Dr. Isbell made with respect to experienced physicians relying on wrong information when forming a diagnosis.

A previously physically normal teen female with a PMHX of depression and anxiety is being transferred from a community hospital after EMS was called to help change her diaper because she would not get out of bed to defecate. She had been admitted 2x in the preceding 3 weeks for "weakness" and both Psychiatry and Neurology had consulted agreeing that the patient suffered from conversion disorder. On the 2nd admission and LP to evaluated for Guillain Barre was normal as was an MRI of the brain and spinal cord. Presently the patient cannot move the lower extremities, has absent DTRs and is suctioning her mouth with a Yankauer due inability to swallow secretions. She is again diagnosed by the peds ER doc (Me) as conversion disorder but cannot be admitted to Psych due to inability to participate in ADLs so is admitted to the floor. After a few days she develops SVT and AMS and a repeat LP is performed showing albuminocytologic dissociation and a Dx of GBS is made.

If you gave me a test and asked: Are the CSF changes of GBS always present at the time of clinical manifestations of sx I would answer "no". And I have cared for patients in the past with a similar scenario. Thus, I had the knowledge and the experience to know better. However, I anchored on the prior workup and allowed the psych-out error and Dx momentum to land on Conversion disorder as the diagnosis. I know the prevalence of neither so arguing that probabilities entered in to my diagnostic reasoning is unsubstantiated.

Good food for thought.

jg
From: Linda M. Isbell [mailto:lisbell at PSYCH.UMASS.EDU]
Sent: Wednesday, November 08, 2017 7:26 PM
To: IMPROVEDX at LIST.IMPROVEDIAGNOSIS.ORG<mailto:IMPROVEDX at LIST.IMPROVEDIAGNOSIS.ORG>
Subject: Re: [IMPROVEDX] The status of heuristics and cognitive biases as a source of diagnostic errors.


Interesting paper, thanks for sharing it; however, I do disagree with the notion that heuristics and biases are not a significant concern in diagnosis.  A large body of research demonstrates the pervasive use of heuristics across pretty much every domain ever investigated over several decades.  This is not at all controversial in psychology.  So, it is unclear to me why diagnosis would be exempt from this - ???  I certainly agree that lack of medical knowledge or experience will certainly lead to diagnostic errors.  However, how do we explain diagnostic errors that emerge when a provider has both knowledge and experience?   One cannot assume, for example, that if an error occurs, one must not have had the knowledge or experience to reach the correct diagnosis (though this can be assessed).  Surely very smart and experienced doctors sometimes rely on the wrong information when assessing patients and forming a diagnosis - the same doctors who may well have the necessary information in their heads but, for some reason, they relied on something other than this information.

Best,

Linda
---
Linda M. Isbell, Ph.D.
Professor, Psychology
Department of Psychological and Brain Sciences
University of Massachusetts
135 Hicks Way -- 630 Tobin Hall
Amherst, Massachusetts 01003
Office Phone:  413-545-5960
Website:  http://people.umass.edu/lisbell/

On 2017-11-07 06:48, Jain, Bimal P.,M.D. wrote:
In this attached paper, I point out that heuristics and biases are a source of inferential errors only in a setting in which the normatively correct method of reasoning is probabilistic.
I argue that the notion of heuristics and biases as a source of diagnostic errors may not be relevant in diagnosis  which  is not probabilistic in practice as I point out in this paper.
I suggest the main sources of diagnostic errors are lack of knowledge and/or experience.
Please review and comment on this paper.
Thanks.

Bimal

Bimal P Jain MD
Northshore Medical Center
Lynn MA 01904.



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