Thursday, March 8, 2012

The two great fallacies of healthcare

I will now attempt my first root cause analysis.  

Actually I'm not even sure I'm using that word in the correct context - I heard it at a "Morbidity and Mortality" conference a while back and now I'm using in a rather cavalier manner.  As long as I'm pretending to be an analyst, I might as well try to use their words.

In true minimalist fashion, let's just cut to the chase.

I will now attempt to explain the root of a host of misconceptions in healthcare.  They are espoused by both patients and physicians alike.

Behold the two great fallacies in healthcare:



I so wish that I was smart enough to come up with those on my own, but I'm not.  They were mentioned almost in passing by a statistics professor that I had in medical school, and for whatever stupid reason those were two of the bits of information that were seared in my memory.  Why couldn't more insightful, useful memories like these have implanted themselves in my brain during my medical school education?  Instead, I paid $245,000 and all I can recall with any sort of detail are the traumatic times like my first rectal exam (thank you to Mr. fake patient guy who offered his rectum to a host of medical students that dreadful October evening).                                            

The truth is that very few - if any - tests in medicine are 100% accurate.  In the medical community we talk in terms of sensitivity and specificity of tests.  This tells us how good a test really is.  A perfect test will have a sensitivity and specificity of 100% and 100%, respectively.  That means it would detect 100% of whatever your test is looking for (sensitivity) and it that test would be 100% accurate for the disease it is looking for (specificity).  Likewise, a terrible test would have be 0% and 0%.

Stick with me - this will all make sense in just a minute.  Consider the following case.
 45 year old female who comes to clinic because of a sore throat (maybe this was you this week).  She wants to know if she has strep throat.  Fair enough.

Capitalism has provided us with a quick, in-office kit to help test for group A streptococcus, the bacteria that causes strep throat.  At first glance it sounds like a great idea, right?  Swab the throat, make a quick diagnosis right there in the room, and be on your way with your prescription in hand.

Not so fast lest you succumb to fallacy #1!  Remember - not all tests are accurate!

As a matter of fact, what would you say if I told you that the commercially available kit only picks up around 75% of strep cases (depends on kit and clinical setting, but values from 65-90% have been reported in the literature).  In other words, if you rely on the test alone, there is a 25% chance that you could actually have strep throat but that the test missed it.  Your doctor tells you that you don't have strep, you go home and develop rheumatic fever, your heart valves are destroyed, and before you know it you've purchased an open-heart surgery complete with have two shiny new mechanical valves.  

I repeat, tests in medicine are not 100% perfect. 

Thus, mammograms miss breast cancers every day.  Colonoscopies miss colon cancer.   CT scans miss intracranial bleeds.  Blood tests miss cirrhosis.  Biopsies miss cancer.  Every test can miss things.  Feeling a little uneasy yet?  

Likewise, all tests can give false positive results.  How many times have your routine blood tests come back "abnormal", only to be repeated and turn out normal?  Now you understand why - all tests are not perfect.  

A major portion of the art of medicine is to understand the limitations of all of the tests that you order.  A well-educated physician will understand the value of a test before he/she orders it and know what a positive or negative test really means - and what to do about it.  That's what we, as internists, do.  We use our brains (theoretically) to determine the pre-test probability of a certain diagnosis, order appropriate tests to pinpoint a diagnosis, and then decide what, if any treatments are appropriate - all the while keeping in mind the two great fallacies of medicine.  This can become incredibly difficult as I will demonstrate later on.

Speaking of treatments, let's move on to the second great fallacy - all treatments are beneficial.

This rule is better understood by physicians than by patients, although we too fall victim.

Here's a scene that plays out every day in America.  Again, you may have been this person.

50 yo M presents to his primary care physician requesting a cardiology consultation to be screened for heart disease after his 50-year old neighbor had a heart attack last week.  He has no cardiac history, no risk factors, and is in very good health.  He runs ultra-marathons, chops timber on his acreage in the woods on the weekends, and has only 2% body fat.  Cardiology consult is ordered and patient sees a cardiologist (the best in town of course!), who in turn orders an exercise stress test (brisk walk on a treadmill with EKG leads on).  The test comes back as slightly abnormal (recall fallacy number one - this particular test is only 75% sensitive and 90% specific).  He is very nervous and fears his life is in danger - after all his neighbor just had 'the big one' last week!  Not to worry, the cardiologist says, let's just do a coronary angiogram to make sure you don't have any significant blockages in your heart vessels.  Besides, he reassures, it's near 100% accurate and is the 'gold standard' test for detecting blockages.  And if we need to, we can stent a blockage while we're in there.  I have a new, state of the art drug-eluting stent that I can deploy if I need to (thank you, and damn you at the same time, capitalism)!  Angiogram is scheduled and he undergoes the procedure.  

During the procedure, however, the cardiologist accidentally tears the patient's main coronary artery and he dies on the table (not an infrequent occurrence).   At autopsy your coronary arteries fail to show any plaque buildup.  In other words, the angiogram was negative.  Oops.  Turns out he stress test was a false positive.  So you've taken a completely healthy 50 year old with no cardiac risk factors, put him through an invasive test that wasn't really indicated, and now he's dead.

Think this is far fetched?  I see it more often than I'd like to admit - not just with angiograms, but with all treatments (surgical as well as medical).  There are risks to EVERYTHING that we do in medicine.  

So what the hell happened?  Both patient (usually ignorantly) and physician (either ignorantly or arrogantly) fell victim to BOTH fallacies.  They trusted that the test was accurate and that the treatment was beneficial.

At this point you should be feeling very vulnerable.  If tests aren't perfect and treatments can be harmful, what the are you supposed to do? 

The answer is quite simple, actually.  You need to find a good doctor.  And you need to trust him/her.

Educated, well-intended physicians understand the limitations of tests and treatments.  That is, after all, the essence of what it means to be a doctor.  Hence the term the art of medicine.  

Crappy physicians (there are plenty to go around) either don't understand this, or even worse, they don't care.  It's much easier to just shotgun off a slew of tests and then react to every abnormality than it is to consider the consequences of how you will handle any abnormality you find.  After all, it's easier not to think!  Insurance doesn't reimburse us nearly as well to think as it does to treat.  Why do you think specialists make 2-5 times what a PCP makes?  We are paid handsomely to do procedures, but little to use our brains.  Is it any surprise then, why we test and treat so much here in America?  We (physicians) are rewarded for that kind of behavior.  

I don't really have a good way to help you know if your doctor is good or not.  But some general observations that I have seen may be able to help you.

First, be wary of doctors who want to test a lot.  Labs, xrays, consultations, medications, etc should not be done routinely for the majority of healthy patients.  Some do it out of ignorance, and others do it because patients generally liked to be tested for things.  Why?  Because they like to be reassured that nothing is 'wrong'.   Now you understand the shortcoming of this logic.  You are assuming that all tests are accurate!  Sooner or later, if you continue to be tested, something will come up abnormal.  Next thing you know, you'll be on the table getting an angiogram and next thing you get the picture.

I'll talk more about screening tests in a future post, because this deserves more attention than I have given it here.  But safe to say, a physician who seems to be 'screening' you for a lot of things when you have no symptoms should make you think twice.

Second, be wary of physicians who don't explain anything to you.  Much of my time is spent telling patients why I am ordering certain tests or offering certain treatments.  Does it take more time out of my schedule?  Yes.  Do I get paid for it?  No.  But it's part of my job, and in good conscience I can't forego this.  Many physicians - perhaps yours - tell you what to do and then don't offer any explaination.  This technique sets the stage for major communication problems and potential bad outcomes.

People innately sense these qualities when dealing with physicians.  Trust your instinct.

Let me conclude with you one more example of how I apply these rules on a daily basis.  Hopefully it will give you an idea of what I do all day, every day.

I recently had an 80 year old M who was admitted to the hospital for abdominal pain and blood per rectum (we find ourselves at the ass once again).  He had longstading pulmonary fibrosis, a condition that slowly scars the lungs until it eventually kills you.  There is no good treatment for it.  He was on oxygen at home.  Despite this, he was very functional, lived alone, and walked a few miles a day.  CT scan showed a large mass in his colon.  Colonoscopy was done, showing a large, fungating mass in the transverese colon that was very suspicious for malignancy.  Biopsies were done, but shockingly came back negative for cancer! 

Further workup revealed a cavitary lung lesion of significant size that could be caused by a number of things - one of which being metastatic cancer. 

So I have a patient that I'm fairly certain has colon cancer, but with a negative biopsy.  What am I supposed to do now?

Recall the two fallacies of healthcare.

First, this gentleman is 80 years old, has never had a colonoscopy, and now has a large fungating mass that is bleeding.  Already my pre-test probability for cancer is somewhere in the 95% region.  The biopsy, however, is negative.  If I stop there and send him home, what happens if it really is cancer and he dies 2 months later?  Oops.  So I ask for a re-biopsy.  Gastroenterologist says thanks but no thanks, that mass is cancer and I'm not going to put him through the risk of another colonoscopy.  Hmm.  Ok.  Next step for a near obstructing colon lesion is surgical removal of the mass.  I consult general surgery.  General surgeon comes by and says there's no way she's operating on him until we prove that this is not metastatic disease (remember he has a lung lesion too) because he is a high-risk surgical candidate given his poor lung function.  She understands (as most surgeons do) that surgery is fraught with risk (see, we're not all ignorant of the great fallacies) and doesn't want to operate if he has widely metastatic disease as it likely won't change the patient's overall outcome.  

So I turn my attention to the lung lesion.  I check a Valley Fever titer via a blood test as he was new to Arizona and Valley Fever is notorious for causing solitary, cavitating lung lesions.    Test comes back positive.  But how good is the test for Valley Fever?  Turns out the screening blood test is not that great, and the number of false positive tests is actually quite high.  Damn.  That's no help. 

Next I order a PET scan.  This is a test that looks for areas of malignancy.  It comes back abnormal - but only mildly so in the colon mass.  Lung lesion does not light up, making cancer less likely (but never ruling it out completely!). 

Now I'm reasonably satisfied (but not totally, of course) that this is a solitary colon tumor without metastasis.  I take this information back to the surgeon.  Sorry she says, after more thought, I'm not convinced this colon mass is a tumor.  She wants another colonoscopy and biopsy.  Gastroenterology balks at it again.  Eventually they agree to take the patient to the operating room, do the colonoscopy in the OR, send it to pathology, and then operate if the repeat biopsy comes back positive.

This whole process to make this decision took about 10 days.

Meanwhile, the poor patient is sitting in his room, eating only liquids because he's scared he'll get an intestinal obstruction if he eats regular food.  He loses 12 pounds.  He's starving.  And he's mad as hell because I can't give him an answer as to what is going on. 

When I finally tell him the plan about the repeat colonoscopy and possible surgery, he gets even more upset.  "Just take the damn thing out," he tells me. "I won't do another colonoscopy.  Just do the surgery and get it out.  I won't do the colonoscopy."  The surgeon did not agree to this (remember - he is high risk for surgery and may have a poor outcome), and she was absolutely right to consider this.  If it turns out its just a benign problem and he dies in surgery, that's not good.

The next morning the patient left the hospital against medical advice.  Just up and left.  Either we did a very poor job of communicating out thought process, or he was being unreasonable.  Probably a bit of both.

I have no idea what happened to him, but there are a few possibilities.

1) He went home, it turned out to be cancer, and he'll now die from it (if he hasn't already).
2) He went to another hospital, found someone willing to operate, and had one of a few outcomes:
            a) this was cancer and he survived the operation;
            b) this was cancer but he died on the OR table (oops);
            c) this wasn't cancer and he survived the operation; or
            d) this wasn't cancer and he died on the table (double oops).

Option B and D are the worst case scenario - 1) because the patient is now dead, and 2) there are scum lawyers out there who make a living off of stuff like this (especially off of D).

Talk about paralysis by analysis.  I'm exhausted just replaying this again in my mind.  And that was just one patient.  Try doing this for 20+ patients every day and now you have a better understanding of what we do. 

At any point along this continuum of care exists a potential for error, malpractice, and bad outcomes.  Why did I sign up for this again?

Now that I've made you feel so insecure about your health, your doctor, and medicine in general, let me offer some reassurance.  These represent a minority of cases.  By and large, doctors are well educated, want to do the right thing, and really do care about our patients. 

But at the end of the day, remember that doctors are imperfect people working with imperfect science.  We miss things.  We make mistakes.  And when we do, we feel terrible about it.  But if nothing else, hopefully we can say we did the absolute best we could with the information that we had.  And we hope that you understand that.

Stay tuned.


  1. This is bloody good my friend...esp "paralysis by analysis." However ultimately I find (although admittedly rarely do I take such initiative, mostly because I am too arrogant and foolishly believe I am making the right&best decision on behalf of the patient based on my objective EBM and subjective common sense with 99% sensitivity and specificity) that as long as we candidly acknowledge/educate/discuss with the patients about 1-2d, they can decide what they what they want done. This may be leaving AMA and ultimately peril and demise 2/2 to Mr. metastatic CA or Mrs. disseminated cocci, or most likely the MI+PNA+PE breakfast special. Which bring us back to your first great point; don't trust physicians that don't explain things to you; this often may reflect that they are too ignorant and clueless to explain what is going on with any amount of statistical or qualitative confidence -_-

  2. your blog is amazing.