Early in my academic career I became fascinated with decision analysis.  I still like decision analysis as a strategy to make explicit the structure of a problem.  However, over time the major weakness of decision analysis became very clear.  The problem derives from the assumptions.

As usual, I will use pharyngitis to frame the problem.  Most articles and all the guidelines make the assumption that we can dichotomize pharyngitis into group A strep pharyngitis or "viral".  The problem here is that the assumption is wrong.

The assumption states implicitly that only group A strep pharyngitis requires antibiotic therapy.  This assumption might work for pre-adolescents, but in adolescents and young adults group C deserves treatment and as I write repeatedly, fusobacterium pharyngitis deserves treatment.

The assumption really explains the difference between the 2 US guidelines.  It explains many attempts to decrease antibiotic use by only treating rapid test positive sore throat patients.  

The authors of these papers also make the assumption that the rapid test is highly accurate.  That assumption may not work either.  Recent data, cited in this blog, call the quoted sensitivity of 90% or greater into question.

When caring for patients, we must always question our own assumptions and the assumptions of other physicians.  We owe our patients great skepticism.  When we take implicit assumptions and make them explicit, we are more likely to challenge the assumptions and adjust our thinking about the patient (or the clinical condition).

Euclid taught me that without assumptions there is no proof. Therefore, in any argument, examine the assumptions. – E. T. Bell
 

This week my team presented a patient who had puzzled them.  The patient complained of 3 weeks of facial swelling.  She had diabetes mellitus type II with severe gastroparesis.  She had both a feeding tube and a port (she used the port for saline boluses when she became volume contracted).

She had gone to several other hospitals and seen more than 5 physicians.  They had made a diagnosis of community acquired pneumonia and given antibiotics.

She came to us still complaining of a cough and chest pain, but mostly complaining of facial swelling and a hoarse voice.

As I listened to the story, I was confused (perhaps because the presenter seemed confused).  We looked at the CXR and suddenly I knew the answer.  My intuition took over.  

I then proceeded to read about my proposed diagnosis prior to going to the bedside.  

At that point I was not considering a differential diagnosis, because I did not feel that I needed system 2 thinking.

I hope you know the diagnosis by now.  If not I will provide some more clues.

At the bedside the patient had a diffusely swollen face and a hoarse voice.  Her neck was too swollen to evaluate her jugular veins.  Her hands and arms were also swollen.

I look at her feet and they were no swollen at all.

We confirmed the diagnosis that afternoon.

I never left system 1 thinking.  Like Klein explains, I just knew the answer.  I had not personally seen this entity in many years, but yet I knew the diagnosis.

Knowing the answer is not enough as Klein explains.  We must also think through the diagnosis and careful examine that diagnosis for potential flaws.  As I considered the diagnosis, I could not find flaws, but rather found increasing evidence to support the diagnosis.

This process of naturalistic decision making likely better explains most of our decision making in medicine.  

When discussing cognition intuition does not refer to ESP, rather definition #3 in dictionary.com - a keen and quick insight. 

Physicians use this form of intuition often.  We learn patterns and use pattern recognition to make quick diagnoses and decisions.  Sometimes we call these patterns "illness scripts".

One can easily argue that experts develop more refined illness scripts over time.  Given these more refined scripts, experts can continue with system1 thinking unless the script is not totally satisfied.  Incomplete scripts or red flags lead experts to switch to system 2 thinking.

Currently I am expanding my understanding of these phenomenon focusing on the work of Gary Klein.  The link takes you to a long overview of his work in Naturalistic Decision Making.  He studies experts who have to make quick decisions, like fireman.  He describes his big break:

Then in 1984, a notice came out from the Army Research Institute asking for proposals about how people make life and death decisions under extreme time pressure and uncertainty.

What he describes runs counter to my previous understanding.  Decision makers under pressure (like physicians) intuitively pick one diagnosis, and then start mentally testing it against their illness script.  If the match raises questions, then they look for an alternate diagnosis.

Experts do not always generate a long list of potential diagnoses.  They only do this when the intuitive process tells them that this problem is too complex for an intuitive answer.

As I read more about this approach, the relevance to internal medicine and family medicine are becoming very clear.  We who teach need to learn to describe our illness scripts.  We need to make explicit the red flags or omissions that make us reject an intuitive diagnosis.  Only through an explicit understanding of a trainees illness script and that script's deficiencies can we help them develop a more advanced script.

I like how Klein describes the process:

That became part of our model — the question of how people with experience build up a repertoire of patterns so that they can immediately identify, classify, and categorize situations, and have a rapid impulse about what to do. Not just what to do, but they're framing the situation, and their frame is telling them what are the important cues. That's why they're always looking, or usually looking, in the right place. They know what to ignore, and what they have to watch carefully.

It's telling them what to expect, and so that's why performance of experts is smoother than the performance of novices, because they're not just doing the current job, they know what to expect next, so they're getting ready for that. It's telling them what are the relevant goals so that they can choose accordingly. 

Time to share a frustration.  While some diseases and symtoms have clear causes, not all do.  If you smoke for 30 years, 2 packs a day, and develop COPD, or coronary artery disease, or lung cancer, then I know why.  If you drink 2 pints of vodka daily and develop cirrhosis, I likely know why.  

If you are promiscuous, or use IV drugs, and develop HIV, I can explain why.

But often I cannot explain why someone develops a disease.  As a physician I have learned that some problems remind me of the old Beach Boys' song – "God Only Knows".

Many patients cannot accept that explanation.  They KNOW that they have a disease because of something they ate (or did not eat).  They are mystified that suddenly they have an illness.  So here is my secret – often we too are mystified.

My advice to patients, if your physician does not have a clear explanation of your disease's origin, then perhaps the origin is not known in 2012.  Maybe in 2020 we can answer the question.

We know more than we did when I started my career.  We now know that most duodenal ulcers arise because of an infection with Helicobacterium pylori.  We now know that cervical cancer follow Human Papilloma Virus infection, that is spread through sexual contact.

Please be patient with us.  We do not have all the answers.  If we say we do not know, please do not ask us probing questions.  We hate saying that we do not know, but sometimes that is just the truth.

Bravo!  As regular readers know, ACP is championing high value, cost conscious care.  Browsing some blogs today I find that the American Journal of Medicine has started a new feature that physicians should consider when trying to provide HVCCC.  Here is the editorial introducing this new feature - Diagnostic Imaging: Powerful, Indispensable, and Out of Control

Today marks the inauguration of a new quarterly venue in The American Journal of Medicine, focusing on Diagnostic Imaging and a wide range of imaging issues germane to the practice of clinical internal medicine. We intend to bring you articles outlining appropriate utilization parameters for different modalities and disease entities; clinical research articles identifying the causes, effects, and costs of suboptimal imaging strategies; cost-benefit analyses of various imaging strategies, and global overviews of the economics of imaging in both the hospital and outpatient settings. Our aim is to educate and inform. More importantly, we hope to initiate an earnest dialogue in the internal medicine community about the proper role of various imaging modalities in clinical practice and begin to understand how we can best approach problems that are well known, easily identifiable, but not yet properly addressed.

So we must congratulate the "green journal" for this important undertaking.  The secret to slowing down and even reversing the continuing increases in health costs will require many interventions.  We must use diagnostic tests more intelligently.  We must use less expensive pharmaceuticals when possible.  We should try to use less prescription meds.  We can only make a difference in health care costs if we pay attention to all these issues and more.

The "green journal' has made an important statement with the release of this feature.  The first entry tells us that we are likely too quick to order repeat abdominal CT scans - 

Dr Ivan Ip et al directly approach the specifics of over-utilization by analyzing the parameters of rapidly increasing repeat abdominal imaging, highlighting the complexity of the larger issues by focusing on one small component, and thereby demonstrating the multifactorial approach that will be needed to address all aspects of this seemingly inexorable problem.

So read the articles and look forward to further entries in this series.

Several readers nailed this one – valproic acid (Depakote).  Valproic acid does cause hyperammonemia

This syndrome can occur with overdoses, but can also occur on apparently stable dosing.

High Value Cost Conscious Care does not just represent a slogan.  HVCCC represents an attitude.  We at ACP believe that physicians can help decrease health care costs.  We see waste in the system and will do our best to decrease the waste.

Yesterday I tweeted - Appropriate Use of Screening and Diagnostic Tests to Foster High-Value, Cost-Conscious Care bit.ly/yIjyP4 via @addthis – must read!

Please read this article.  This represents a real attempt to provide practical guidelines (with a small g) on ways to avoid unnecessary testing.  This article is just the beginning.

We physicians have a responsibility to the nation to decrease costs when doing so has no negative impact on health care.  We must look carefully at eliminating unnecessary testing, drugs and procedures.

From this article I particularly like these quotes:

Finally, it is important to note that the true cost of a test includes not only the cost of the test itself but also the downstream costs incurred because the test was performed (5). For example, an exercise stress test in an asymptomatic patient may result in a false-positive finding that leads to cardiac catheterization, with its attendant costs and risks, but with no proven benefit. Thus, a seemingly inexpensive test can result in substantial costs because of subsequent testing, treatment, or follow-up. In assessing the costs of a diagnostic test, we must consider these downstream costs and savings.

Because of this article's importance, the Annals of Internal Medicine has made the text and the pdf free online!
 

Patient admitted after apparent overdose.  Patient does not respond to verbal stimuli or tactile stimulation. Patient has known schizophrenia.

Exam comatose, VS T 99, P 80, R 18, BP 130/80

Otherwise exam is unremarkable

Labs

WBC 7.9

Hgb 12.9/ Hct 37.1

Plt 194

NH₃ 28

4 hours later

Labs

ABG on room air

pH 7.45

pCO₂ 29

pO₂ 126

HCO₃ 20

NH₃ 98

Can you guess what the overdose included?

First, a disclaimer – I am biased.  I have spent 30 years thinking, researching and writing about adult pharyngitis.  My success in that field has stunned me.  Of course I will overemphasize all arguments in favor of my opinion and poo-poo those in opposition.

The advocates of the rapid strep test make these assumptions:

1. We should treat group A strep pharyngitis with antibiotics (preferably a penicillin or a cephalosporin).
2. No other cause of pharyngitis deserves antibiotics.
3. We should avoid antibiotics in all other pharyngitis as that increases the probability of antibiotic resistance.

They implicitly seem to assume that pre-adolescent pharyngitis studies apply to adolescents and young adults (older adults get pharyngitis much less commonly).

They also generally believe the manufacturers claim that the sensitivity of the rapid strep test is > 90%.

Lessons from Medicare’s Demonstration Projects on Disease Management, Care Coordination, and Value-Based Payment

Here are the lessons:

For disease management programs - 

On average, the 34 programs had little or no effect on hospital admissions. There was considerable variation in the estimated effects among programs, however (see figure below).

In nearly every program, spending was either unchanged or increased relative to the spending that would have occurred in the absence of the program, when the fees paid to the participating organizations were considered.

Programs in which care managers had substantial direct interaction with physicians and significant in-person interaction with patients were more likely to reduce Medicare spending than other programs. But, on average, even those programs did not achieve enough savings to offset their fees.

For value-based payment:

Only one of the four demonstrations of value-based payment has yielded significant savings for the Medicare program. In that demonstration, Medicare made bundled payments to hospitals and physicians to cover all services connected with heart bypass surgeries, and Medicare spending for those services declined by about 10 percent. The other demonstrations appear to have resulted in little or no savings for Medicare. One, the Physician Group Practice Demonstration, allowed large multispecialty physician groups to share in estimated savings if they reduced total Medicare spending for their patients. Another offered hospitals bonuses if they met certain criteria regarding the quality of care. The last (for which results are available only on a preliminary basis for the first year) allowed home health agencies to share in estimated savings if they reduced total Medicare spending for their patients and met certain targets for quality of care. 

Boys and girls, this stuff is much more complex than these demonstration projects can address.  Physicians really do their best out there.

We should modify our payment system.  First, we must make our payment system time based.  We have too many patients seen too quickly.  Second, we should invest in the best method for decreasing costs and increasing value – solid outpatient family medicine and internal medicine.

These programs, in my opinion, have too much complexity.  We can save much money by changing our payment system away from the RBRVS formulas.  RBRVS was an interesting idea, but too easy to "game".  We must value time.  We should put a modest value on subspecialized expertise, but much smaller than our current system.