Diagnostic time out

What is a diagnostic time out? Succinctly defined, it’s a deliberate exercise in differential diagnosis and systematic clinical reasoning in the care of an individual patient. But wait, I hear someone say… isn’t that what we do already? Well, no. We’re all familiar with the traditional model for clinical reasoning that we’re taught in medical school but those of us in the real world of practice nowadays, if we’re honest, realize that it seldom happens. There’s just not enough time when you’re forced to see too many patients each day. And hospitalist incentives, with their emphasis on speed and quick adoption of specific diagnostic labels, run in opposition. What do we as hospitalists do instead? Well, aside from all the care pathways and metric incentives that tell us what to do, we rely on clinical instincts and rules of thumb. Because they bypass formal analysis, they save time. They serve as cognitive shortcuts. We call these heuristics. This method of thinking (fast, instinctive, intuitive) is sometimes known as system 1 thinking. It has the advantages of being efficient and fast and sometimes, in critical situations, life saving. But it comes at the cost of a certain error rate. In order to better understand the process of system 1 thinking we have given the various heuristics names and categories. I recently listed some of those in this post. 

If system 1 is our usual measure of processing to get around time constraints the alternative is system 2: formal clinical reasoning .  System 2 thinking was the topic of a recent paper in CriticalCare Clinics. Although based on a survey of people working in a NICU the article has general applicability. The authors contrast system 1 and system 2 thinking in this manner:

Dual process theory holds that individuals engaging in medical decision-making use one of 2 distinct cognitive processes: a system 1 process based on heuristics – the use of rapid pattern recognition and rules of thumb – or a system 2 process, based on deliberate analytical modeling and hypothesis generation. While invoking system one processes individuals can think fast and reflexively and can even operate at a subconscious level, using pattern recognition to sort vast amounts of clinical information quickly before an illness script that allows for the rapid elaboration of a differential diagnosis. In contrast system 2 processes require focused attention and are purposefully analytical, relying on deliberate counter-factual reasoning to generate hypotheses regarding the pathophysiologic mechanisms by which a patient’s symptoms are produced.

The authors introduced the concept of the diagnostic time out to describe this shift of thinking because it requires deliberate effort. It’s not going to arise spontaneously in the natural course of the ward routine. (The authors were not the first ones to use this term). The diagnostic time out can be considered the cognitive equivalent of the better known procedural time out.

Why is a diagnostic time out needed? Research on diagnostic error has indicated that while some instances are due to system problems (such as failure to communicate test results) most are cognitive errors. These can be linked to the heuristics of system 1 thinking. The diagnostic time out, or the deliberate exercise of system 2 thinking, is a way to complement these cognitive shortcuts with a more analytical process.

Some opinion leaders in the field of diagnostic error have suggested universal adoption of system 2 thinking. This is problematic due to time constraints. Besides, there are some essential benefits of system 1 thinking, particularly in acute life-threatening situations. The real trick is how best to selectively employ system 2 thinking. In other words what are the situations in which system 2 thinking should be used? The authors suggest handoff situations in complex patients including ER to hospitalist, off service/on service and ICU to ward transfers.

How does it work? The authors propose a template but it’s really just the traditional clinical reasoning process. One of their points really got my attention: during the time out diagnostic labels should be removed and replaced by signs, symptoms, manifestations and clinical concerns. This of course is the opposite of what your coders and hospitalist leaders want you to do.

What are some of the barriers to implementation? In addition to time constraints, fear of ambiguity is an important factor. We are afraid to admit what we don’t know. One thing you will never hear a hospitalist say out loud is “I’ll have to think about that.”

A little more on metacognition

This article from Academic Emergency Medicine, published in 2002, remains applicable today. It makes the point that heuristics in medicine are valuable even though they can lead to error. The article also makes the statement:

The increasing use of clinical decision rules, as well as other aids that reduce uncertainty and cognitive load, e.g., computerized clinical decision support,will improve certain aspects of clinical decision making, but much flesh-and-blood clinical decision making will remain and there will always be a place for intuition and clinical acumen.

It presents an exhaustive list with detailed descriptions of the various cognitive shortcuts.

Indulge me in a little metacognition

I found an interesting post about cognitive shortcuts in medicine. I have a minor objection to the title of the post which is Cognitive Errors. Cognitive shortcuts, known as heuristics, which are examples of fast instinctive thinking (system one), often lead to error. In some cases, however, they can be useful because they are efficient and time saving. There is an up side as well as a down side to system one thinking in medicine.

Let’s go down the list. I’ve skipped some of them.

The first example given is affective error. This refers to an emotional response surpassing objectivity.

Next is aggregate bias. I struggle with this one. The author says that the aggregate bias is the belief that data in the aggregate don’t apply to the patient in front of you. My understanding (maybe I’m wrong) is that aggregate bias, otherwise known as the ecological fallacy, is the opposite. That is, it refers to inappropriate application of population data to an individual. It has more to do with treatment decisions than diagnostic error. Remember, one of the first principles of evidence-based medicine is that clinical reasoning decision making starts with the unique aspects of the individual patient. After looking at a variety of references, it would appear that both definitions have been used. Most medical references define aggregation bias the way the blog author does. Those outside of medicine define it as inappropriate extrapolation.

The ambiguity effect is really a bias against ambiguity. So we tend to stick with things we are more familiar with. That may cause us to ignore other possibilities and take too narrow a view of things. As originally conceived it had to do with probability. That is, people have a tendency to gravitate toward choices in which the probability is known or explicitly stated. Of note, the ambiguity effect was first described by Daniel Ellsberg.

The anchoring heuristic is one of the better known cognitive biases. This refers to the tendency to stick with one’s initial hunch despite new evidence to the contrary. You may be so proud of your initial hunch that you ignore new information. Confirmation bias and diagnostic momentum are related concepts.

Ascertainment bias, as the author points out, is an umbrella category. It encompasses a lot of stereotypes and biases. In essence it’s just—-well, bias. It’s not very useful as a unique category in discussions of cognitive error.

Availability bias is one of the better known cognitive shortcuts. This refers to the influence of prior experience. This causes bias toward the first thing that comes to your mind. For example, if you’ve been burned by having missed a case of aortic dissection you may tend to be over concerned about aortic dissection in every future case of chest pain. The flip side is you may fail to consider things you haven’t seen in a long time.

Base rate neglect is a cognitive shortcut that may be considered harmful and wasteful in ambulatory medicine but may be your friend in the arena of hospital and emergency medicine. It’s a failing to consider the true prevalence of diseases in clinical reasoning. It ignores the old aphorism “common things happen most often.” In the high acuity world of the hospital, where you really need to be risk-averse, base rate neglect may be beneficial. Put another way you and and your patient may be better off if you consider worst case scenario.

Then there’s belief bias. I’m not sure this belongs in a discussion of diagnostic shortcuts as it has more to do with treatment recommendations. I cringe when I hear somebody say they “believe“ in a particular treatment, implying that belief surpasses reasoning from evidence .

Blind spot bias is similar to the Dunning Kruger effect in which we think we're smarter than we really are. Humility is the remedy here. Does this lead to a form of cognitive shortcut? Maybe in that we fail to pause and consider carefully that we might be wrong.

Confirmation bias is akin to anchoring. This is the tendency to be selective in what type of accumulating evidence you consider. That is, you consider mainly evidence that supports your original hunch.

The framing heuristic is another well known shortcut. We are biased toward diagnostic possibilities in accordance with the way the initial presentation is framed. Though it can be useful it restricts our differential diagnosis in a way that excludes a wide range of possibilities. Not every returning travel with fever has a parasite, for example.

The gamblers fallacy, according to the blog author, is “the erroneous belief that chance his self correcting.“ This is a cognitive error that tends in the opposite direction to the availability heuristic.

The order effect is something I was vaguely aware of but had not considered as a cognitive error category. It refers to the tendency to focus on information that is proximate in time and to do so at the expense of the totality of events over time. This typically occurs at the point of hand off in a patient who has had a very long hospital course.

Premature closure is just what it says. It’s a tendency for thinking to stop once a tentative diagnosis has been made. It overlaps with other categories such as anchoring. There is probably a subtle difference between premature closure and anchoring. Anchoring implies an emotional attachment to a diagnosis whereas premature closure implies diagnostic laziness.

Representativeness restraint has also been known as a representativeness heuristic. It is a cognitive shortcut characterized by focusing too much on the prototypical manifestations of a disease. This may cause the clinician to miss atypical presentations.

Search satisfaction is another example of laziness in clinical reasoning. It’s a tendency to stop searching once an answer has been found. The author gives the example of missing a second fracture on an x-ray once the first one is identified.

Sunk cost fallacy is a type of emotional heuristic as well as diagnostic laziness. It is the tendency to ignore new information and not consider alternative diagnoses once the original diagnosis has been arrived at after a great time effort and expense (the sunk cost).

Sutton’s slip might be the dark side of Sutton’s law (going where the money is). Pursuing the obvious might lead to error because of other possibilities being ignored.

Zebra retreat is the avoidance of rare diagnoses to a fault. It’s an opposite of base rate neglect.

Psychological benefits of a single exercise session

Systematic review here.

Recent psychiatric hospitalization was associated with an increased risk of stroke

---in this study.

Pain dogma reversal at SHM

Medscape reported on the pain management sessions at SHM 2017 in an article titled Rethinking Pain Can Help Hospitalists Fight Opioid Crisis. I did not attend that year but from the sound of the article it was more like a complete reversal than a rethinking, and a reversal is what is needed.

Starting in about 1999, when this movement was launched, uncontrolled pain was the big public health crisis. Now it’s the opioid crisis. How interesting.

From the beginning of the “fifth vital sign” movement SHM (then known as NAIP, the National Association of Inpatient Physicians) was in lockstep and served up its share of the prevailing dogma. It’s particularly interesting that this occurred when evidence based medicine was the hot new thing, just 7 years following its launch. Near the top of everyone’s mind was the notion that science was here to replace dogma. Except, apparently, when the discussion was about pain. As I read the Medscape piece numerous then and now contrasts started swirling through my mind. I wish I still had my notes from NAIP and SHM sessions of past years but I don’t so I’ll have to do this from memory. I’ll cite a couple of comments from the article followed by my recollections of meetings past:

From the 2017 sessions:

"The message to patients should not be that the goal is to become pain free," she explained. "We should not be expecting opioids to decrease pain by more than 20% to 30%."

Old dogma: nearly all pain can be eliminated and no hospitalized patient should have to endure pain.

"The pattern of reflexively prescribing opioids when a patient in the hospital reports a high pain score needs to be broken, she said."

Old dogma: opioids are just fine. Concerns about addiction are  largely driven by myth. Take patients’ reports of their pain at face value.

Did anyone at SHM stand up and say “we were wrong”?

The neuropsychology of morbid obesity

Several cognitive defects noted in this study.

Neuropsychiatric complications of dopaminergic therapy

As pointed out in this free full text review the neuropsychiatric side effects go beyond impulsive gambling to a variety of impulse control phenomena and other psychiatric disturbances. Moreover, it’s not just in patients treated with Parkinson disease but also some of those treated for restless leg syndrome and prolactinoma. There are a number of poorly understood metabolic effects as well, largely favorable it would seem.

Muscle dysmorphia: a new disease?

From BMC Psychology.

Antidepressants really do work after all

The narrative for the last decade was that they didn’t, and that their use was a pharma conspiracy. Nice post at SBM. (Oh, but wait! One of the authors of the primary source is John Ioannidis! Does that make this paper one of the few research reports that’s actually true?).

Climate change and the coming mental health apocalypse

You can read the entire Medscape report here but the long and the short of the report is that yes people get stressed out over weather events, along with multiple disclaimers that no, this is not politically motivated.

ADD medicines may help prevent MVAs

From JAMA Psychiatry:

Design, Setting, and Participants For this study, a US national cohort of patients with ADHD (n = 2 319 450) was identified from commercial health insurance claims between January 1, 2005, and December 31, 2014, and followed up for emergency department visits for MVCs. The study used within-individual analyses to compare the risk of MVCs during months in which patients received ADHD medication with the risk of MVCs during months in which they did not receive ADHD medication.

Exposures Dispensed prescription of ADHD medications.

Main Outcomes and Measures Emergency department visits for MVCs.

Results Among 2 319 450 patients identified with ADHD, the mean (SD) age was 32.5 (12.8) years, and 51.7% were female. In the within-individual analyses, male patients with ADHD had a 38% (odds ratio, 0.62; 95% CI, 0.56-0.67) lower risk of MVCs in months when receiving ADHD medication compared with months when not receiving medication, and female patients had a 42% (odds ratio, 0.58; 95% CI, 0.53-0.62) lower risk of MVCs in months when receiving ADHD medication. Similar reductions were found across all age groups, across multiple sensitivity analyses, and when considering the long-term association between ADHD medication use and MVCs. Estimates of the population-attributable fraction suggested that up to 22.1% of the MVCs in patients with ADHD could have been avoided if they had received medication during the entire follow-up.

Conclusions and Relevance Among patients with ADHD, rates of MVCs were lower during periods when they received ADHD medication. Considering the high prevalence of ADHD and its association with MVCs, these findings warrant attention to this prevalent and preventable cause of mortality and morbidity.

Dexmedetomidine versus haloperidol in delirious non intubated ICU patients

From a recent paper:

Objectives: To evaluate the clinical effectiveness, safety, and cost of dexmedetomidine for the treatment of agitated delirium refractory to haloperidol in nonintubated critically ill patients.

Design: Nonrandomized, controlled trial.

Setting: Intensive care department of a tertiary care nonprofit hospital.

Patients: All consecutive admissions to a medical-surgical ICU with a diagnosis of agitated delirium.

Interventions: Initial haloperidol titration: all patients received IV bolus doses of haloperidol until agitation was controlled (Richmond Agitation Sedation Scale scoring range, 0 to −2) or reaching the maximum daily dose. Group comparison: patient responders to haloperidol (control group) were compared with nonresponders (dexmedetomidine group).

Measurements and Main Results: A total of 132 nonintubated patients were treated with haloperidol in the initial haloperidol titration phase. Forty-six patients (34.8%; 95% CI, 26.0–43.1%) did not respond to haloperidol, and 86 patients (65.2%; 95% CI, 56.3–73.0%) were responders. During the group comparison phase, dexmedetomidine achieved a higher percentage of time in satisfactory sedation levels than did haloperidol (92.7% [95% CI, 84.5–99.8%] vs 59.3% [95% CI, 48.6–69.3%], respectively; p = 0.0001). Haloperidol was associated with 10 cases (11.6% [95% CI, 6.5–21.2%]) of oversedation and two (2.0% [0.4–8%]) of corrected QT lengthening. Direct cost of dexmedetomidine was 17 times greater than haloperidol, but it achieved a mean savings of $4,370 per patient due to the reduction in length of ICU stay.

Conclusions: In the study conditions, dexmedetomidine shows to be useful as a rescue drug for treating agitation due to delirium in nonintubated patients in whom haloperidol has failed, and it seems to have a better effectiveness, safety, and cost-benefit profile than does haloperidol.

Panic disorder and coronary heart disease

A recent systematic review suggests a link:

Method. Relevant studies were retrieved from Medline, EMBASE, SCOPUS and PsycINFO without restrictions from inception to January 2015 supplemented with hand-searching. We included studies that reported hazard ratios (HR) or sufficient data to calculate the risk ratio and 95% confidence interval (CI) which were pooled using a random-effects model. Studies utilizing self-reported CHD were ineligible. Twelve studies were included comprising 1 131 612 persons and 58 111 incident CHD cases.

Results. PD was associated with the primary incident CHD endpoint [adjusted HR (aHR) 1.47, 95% CI 1.24–1.74, p less than 0.00001] even after excluding angina (aHR 1.49, 95% CI 1.22–1.81, p less than 0.00001). High to moderate quality evidence suggested an association with incident major adverse cardiac events (MACE; aHR 1.40, 95% CI 1.16–1.69, p = 0.0004) and myocardial infarction (aHR 1.36, 95% CI 1.12–1.66, p = 0.002). The risk for CHD was significant after excluding depression (aHR 1.64, 95% CI 1.45–1.85) and after depression adjustment (aHR 1.38, 95% CI 1.03–1.87). Age, sex, length of follow-up, socioeconomic status and diabetes were sources of heterogeneity in the primary endpoint.

How does stress make you sick?

The Holmes- Rahe Stress Inventory has been around for years. I remember it from one of my college psychology classes. The idea is that if you score over a certain level on this survey chances are you'll get sick in some way, pretty soon. Intuitively it makes sense and there are multiple lines of evidence, some strong and some not so strong, as to various mechanisms. One, according to a recent study, is telomere shortening.

Ketamine for rapid reversal of depression and suicidal ideation

From a recent study:

We have previously shown that a single dose of ketamine, a glutamate N-methyl-d-aspartate (NMDA) receptor antagonist, is associated with a rapid reduction in depressive symptom severity and SI in patients with treatment-resistant depression.

Method. We conducted a randomized, controlled trial of ketamine in patients with mood and anxiety spectrum disorders who presented with clinically significant SI (n = 24). Patients received a single infusion of ketamine or midazolam (as an active placebo) in addition to standard of care. SI measured using the Beck Scale for Suicidal Ideation (BSI) 24 h post-treatment represented the primary outcome. Secondary outcomes included the Montgomery–Asberg Depression Rating Scale – Suicidal Ideation (MADRS-SI) score at 24 h and additional measures beyond the 24-h time-point.

Results. The intervention was well tolerated and no dropouts occurred during the primary 7-day assessment period. BSI score was not different between the treatment groups at 24 h (p = 0.32); however, a significant difference emerged at 48 h (p = 0.047). MADRS-SI score was lower in the ketamine group compared to midazolam group at 24 h (p = 0.05). The treatment effect was no longer significant at the end of the 7-day assessment period.

Conclusions. The current findings provide initial support for the safety and tolerability of ketamine as an intervention for SI in patients who are at elevated risk for suicidal behavior. Larger, well-powered studies are warranted.

Well, this is intriguing but I am a little concerned about the use of midazolam for the comparison group. How do we know it didn't make the depression worse? Apparently though, according to the abstract above, there are previous data suggesting a beneficial effect of ketamine so this warrants further investigation.

Depression and autoimmune diseases

Is there a link?

Remission of adult ADHD

From a recent study:

Method A 7-year follow-up study of adults with ADHD (n = 344, mean age 34.1 years, 49.9% males) was conducted. Variables from different domains (social demographics, co-morbidities, temperament, medication status, ADHD measures) were explored with the aim of finding potential predictors of ADHD persistence.

Results Retention rate was 66% (n = 227). Approximately a third of the sample (n = 70, 30.2%) did not maintain ADHD criteria and 28 (12.4%) presented full remission (less than 4 symptoms), independently of changes in co-morbidity or cognitive demand profiles. Baseline predictors of diagnostic persistence were higher number of inattention symptoms [odds ratio (OR) 8.05, 95% confidence interval (CI) 2.54–25.45, p less than 0.001], number of hyperactivity/impulsivity symptoms (OR 1.18, 95% CI 1.04–1.34, p = 0.01), oppositional defiant disorder (OR 3.12, 95% CI 1.20–8.11, p = 0.02), and social phobia (OR 3.59, 95% CI 1.12–11.47, p = 0.03).

Mood disorders predispose youth to precocious cardiovascular disease

---according to an AHA statement.

Concerning possible mechanisms, according to the paper:

In this scientific statement, there is an integration of the various factors that putatively underlie the association of MDD and BD with CVD, including pathophysiological mechanisms, traditional CVD risk factors, behavioral and environmental factors, and psychiatric medications.

Exercise as treatment for depression

From a JAMAClinical Evidence Synopsis:

Bottom Line Exercise is associated with a greater reduction in depression symptoms compared with no treatment, placebo, or active control interventions, such as relaxation or meditation. However, analysis of high-quality studies alone suggests only small benefits.