The Skeptical Clinician

All scientists should be skeptics. Serious problems arise when a less-than-skeptical approach is taking to the task of discovery. Typically the result is flawed science, and for those significantly lacking in skepticism this can descend to pseudoscience and crankery. With the applied sciences, such as the clinical sciences of medicine and mental therapy, there are potentially immediate and practical implications as well.

Clinical decision making is not easy, and is subject to a wide range of fallacies and cognitive pitfalls.  Clinicians can make the kinds of mental errors that we all make in our everyday lives, but with serious implications to the health of their patients. It is therefore especially important for clinicians to understand these pitfalls and avoid them – in other words, to be skeptics.

It is best to understand the clinical interaction as an investigation, at least in part. When evaluating a new patient, for example, there is a standard format to the “history of present illness,” past medical history, and the exam. But within this format the clinician is engaged in a scientific investigation, of sorts. Right from the beginning, when their patient tells them what problem they are having, they should be generating hypotheses. Most of the history taking will actually be geared toward testing those diagnostic hypotheses.

For example, if a patient is being seen with a headache they may relate that the pain is most severe in the front of the head and extends down into the face. This could be a migraine headache, or a sinus headache, or less likely due to an underlying serious pathology. The physician may then ask if the patient has nasal congestion – this is not a random or screening question, but is designed specifically to test the hypothesis that the headache may be a sinus headache. During the exam the physician may also apply pressure to the sinuses to see if they are sensitive, and perhaps even this reproduces the patient’s headache.

This seems rather straightforward, but actually all of the potential pitfalls of scientific investigation are in play. For example, while it is necessary to ask specific questions to test diagnostic hypotheses, this can easily lead to confirmation bias. Let’s say a clinician asks patients with frontal headaches if they have nasal congestion, and 40% of them (to use a hypothetical figure just for illustration) say that they do. This might lead the clinician to conclude that this is an important finding, and that it confirms that many patients with frontal headaches probably have sinus headache. What we do not tend to do, however, is institute a control  – in this case ask patients with posterior headaches if they have nasal congestion, or patient without headaches. Perhaps 40% of all patients report nasal congestion.

This fallacy is similar to the toupee fallacy – believing that one can always recognize a toupee. This may be due, however, to not being aware of (and therefore not counting) instances when you cannot recognize a toupee. In diagnostic terms, signs and symptoms may seem to correlate strongly with a certain clinical presentation, but that can be an illusion of confirmation bias; only looking for the correlation to confirm your suspicions.

This is exactly why we need controlled data to guide our clinical assessments. What the clinician really needs to know, for example, is what the predictive value of having sinus congestion is for someone who presents with a frontal headache.

Another way to look at this is that anecdotal experience can be misleading, while carefully collected scientific data is reliable and predictive. This not only applies to questions about which treatments are safe and effective, but to the application of those treatments to individual patients.

Clinicians are also prone to correlation fallacies – assuming causation from correlation and temporal sequence (post hoc ergo propter hoc). This may be especially true for apparently good responses to our treatments. If I give that patient a treatment for their headaches and the headache gets better, it is very tempting to take credit for the improvement. We need to recognize, however, that the improvement may have been entirely coincidental, or due to placebo effects. This has practical implications going forward. If the headache recurs, will the same treatment also be effective? If the treatment has side effects, are they worth it? There may also be diagnostic implications – if I gave the patient a migraine-specific treatment and they improved, does that mean they have migraines?

There are other aspects of gathering the patient’s medical history that require the constant application of skepticism. First, the history is being filtered through a person (usually the patient, but perhaps a family member or other caregiver). This means the history is subject to all the flaws of human memory. Memories can be confused, fused, and altered over time. Every time you remember something you are actually reconstructing and potentially changing the memory. This process is exacerbated with a medical history, and a patient may have told their history to many individuals. There is therefore a large potential for contamination. Every time an interviewer asks a question they are potentially contaminating the patient’s memory with the content of that question.

There are also phenomena known as source amnesia and truth amnesia – we are better at remembering facts than we are at remembering where they came from (the source) and whether or not they are even true. So patients may relate a lot of information about this prior history, workup, treatment, and diagnosis while being confused about where the information came from, or even if it is true or not.

Clinicians can also make the mistake of assuming that because a bit of patient history is written down in the chart it is more likely to be true. This is not necessarily the case, however. There is what we call “chart lore” – facts passed on from one clinician to the next as part of the history but never traced to the original source. Each person just assumes the last person checked it out before they wrote it down. I frequently see patients who are walking around with medical diagnoses they don’t have. One clinician told them they might have a diagnosis, or even that the chance that they have it is very low, or perhaps that they don’t have a diagnosis. They, however, leave with the impression that they do have the diagnosis, and they pass that on to the next clinician they see, who writes it down as part of their history.

Further, we need to recognize that each patient has their own narrative – the way in which they understand and perceive their own health and illness. This narrative then affects all the information they have about their illness – what they choose to reveal, what they don’t reveal, the timing of events, the chain of cause and effect, and what labels they accept. The clinician has to simultaneously understand this narrative and investigate what is objectively going on that has led to this narrative. The narrative is important because it will influence how we communicate to the patient and make treatment decisions with them.

But we should not confuse this narrative with reality. The job of the clinician is to be detached, to step back and try to look through the narrative, the chart lore, the logical fallacies, imperfect memory, and all the rest to figure out what is really going on. In other words, the clinician has to be skeptical – skeptical of every piece of information and how it is interpreted, and skeptical of themselves and their own biases and desires.

This, of course, is an idealized goal, something we need to continuously strive for but probably never attain. Perhaps the most pernicious aspect of the current infatuation with unconventional treatments is that they overtly promote gullibility rather than skepticism on the part of the clinician (and everyone else).  This is partly why unscientific medicine cannot be “integrated” into science-based medicine – they are fundamentally philosophically incompatible. Practicing science-based medicine requires rigor and skepticism, while the “alternative” requires a surrender to gullibility and naivete.

Posted in: Science and Medicine

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12 thoughts on “The Skeptical Clinician

  1. thatguybil81 says:

    “Clinical decision making is not easy, and is subject to a wide range of fallacies and cognitive pitfalls.”

    This is something that Clinical Decision Support Software tries to address, but more often then not fails. Some vendor solutions are better then others, but I have yet to see one that “works”.

    Narrowly focused ones (Sentri7 for ID) tend to be better then broadly focused CDS, but they still come up short.

  2. DugganSC says:

    I feel like this is an apropos place to put House’s line that “people lie” which he uses to justify everything from breaking into patient apartments to misleading people on what their diagnosis is to trying random treatments on the off chance the patient is faking or is mistaken about a symptom. In actuality, of course, his approach is untenable because he always assumes there’s something the patient isn’t telling him (generally true due to the format of the show) whereas the truth of most diagnoses is that most patients do provide most of their symptoms and approaching the symptoms from the perspective that they’re certainly false is no better than approaching them with the perspective that they’re certainly true.

    Personally, as a patient, I’m always a bit afraid to list symptoms that are unrelated to what I believe I have for fear that the doctor, hearing hoofbeats and seeing stripes, will assume zebras and refuse to admit that I’m a referee who’s been trampled by horses. I know it’s somewhat silly, but it’s a fact of life for me. That and, of course, you run the risk of side symptoms being treated rather than the condition. I went to three different doctors with the complaint of pressure buildup in my ears before an ENT treated my allergies (and then charged me for three hearing tests that he insisted were part of the standard procedure for checking problems with pressure in the ears), which cleared up the problem. The prior two gave me solutions for my cold and for neck pain, both of which were side symptoms I had at the time.

    Ultimately, it’s a tricky thing. Sometimes those spurious symptoms are influencing the problem. Sometimes, it seems the doctor solves them because they know how to solve them versus what you actually came in for.

  3. thatguybil81 says:

    “I’m always a bit afraid to list symptoms that are unrelated to what I believe I have for fear that the doctor, hearing hoofbeats and seeing stripes, will assume zebras and refuse to admit that I’m a referee who’s been trampled by horses.”

    Thats a new twist on an old phrase. :)

  4. jt512 says:

    This is partly why unscientific medicine cannot be “integrated” into science-based medicine – they are fundamentally philosophically incompatible. Practicing science-based medicine requires rigor and skepticism, while the “alternative” requires a surrender to gullibility and naivete.

    That was a very incisive conclusion. I had never thought of it that way.

  5. tgobbi says:

    At the risk of being accused of “hippothanatology” (not a real word, but if it were, it would mean “beating a dead horse”), I once again chime in complaining that too many MDs eschew skepticism and suggest acupuncture for my chronic neck pain.

    It’s happened a number of times; my new pcp, physiatrists and anesthesiologists, for example, on discovering that I’ve undergone surgery, PT (on at least 5 separate occasions), trigger point injections, cervical epidural and cervical facet injections (5 times between them), traction, NSAIDs, opiates (need I go on?) – all without success – all have suggested, or at least asked if I’ve considered, acupuncture. The good news is that they drop the subject as soon as I challenge them to refer me to a reliable study that demonstrates better results than those of placebo.

    Ironically, for the record, I get the most relief from over-the-counter Aleve!

  6. Kultakutri says:

    It happens me way too often that I say I’m on long-term antidepressants and doctors conclude (a) whatever my complaint is, it’s psychosomatic (b) I’m a fragile nervous irritable person (c) my complaint is certainly a side effect of my antidepressants (d) it’s stress… and variants of thereof. Admittedly, it’s probably hard to say when I’m not bleeding or oozing pus. {sarcasm}

  7. gziomek says:

    While working at a local health-food store (partially what got me into skepticism), I met a woman that had me run all over the vitamins and supplements section finding things that she said her doctor wanted her to have for conditions x, y, and z. After talking to her for a while, she eventually told me that her “doctor” was just a book of natural remedies, etc.

    I wonder if the next time she sees a physician, she refers to the book as her “doctor” again. Either way, I hope the next doc she sees has this same line of skeptical thinking.

  8. Adam Rufa says:

    I am starting to develop an elective for PT students about the topic of critical and skeptical thinking. Thanks for this great post which will help me as I put together this elective!

  9. jmm says:

    This post struck a chord with me. I just saw 4 different docs over 7 weeks (one PCP, one emergency doc, 2 specialists), before the last of the four finally asked the right questions and listened long enough to change my diagnosis from asthma to vocal chord dysfunction. That included an asthma/allergy specialist who did not ask me a SINGLE question about my symptoms, did spirometry only my exhale (which was above normal), told me that the allergy skin tests he had just done were “very sensitive” when I asked him about false positive rates, and then when I tried again, pointing out that false positives refer to the specificity not the sensitivity, told me that because we knew from my symptoms that I had allergies, this was not something I needed to know. Luckily, this doc was so obviously bad that it was abundantly clear to me that I had to seek a second opinion, but when issues like this are more subtle or when patients are less educated than me, then this behavior passes unnoticed.

    What I don’t understand is why your column focuses so much on CAM. My recent experience is not uncommon, and I wish you folks at SBM would put more effort into scrutinizing the regular medical system, in an attempt to reduce the frequency of experiences such as the one I just had.

  10. Scott says:

    Mainstream medicine is indeed criticized here when it departs from a proper scientific backing. But since the overwhelming majority of the antiscience in medicine is CAM, it gets a corresponding majority of the attention.

  11. rwk says:

    Your post summarizes this site perfectly. Don’t expect any of the usual bloggers here to agree with you.

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