Wednesday, January 26, 2005

Diagnosing: Occam vs. the Saint

The plight of the engineer with two "zebra" diagnoses has drawn more e-mail. Another patient tells of a hard-to-diagnose heart problem:

"I just returned from having corrective surgery (RF ablation) done to correct afib episodes. I went 16 years without a diagnosis of my heart problem, and had accepted early on that I knew something was wrong with my heart and that no doctor was going to recognize that fact." He's written about the stress caused by his illness. There's a happy ending. He's improving now. He seems delighted with his current medical care. But why did he have to wait sixteen years?

How do we try to figure out what's wrong with someone? We usually start with "Occam's razor," looking for the simplest explanation for the patient's symptoms. And when Occam fails us? Here's e-mail from Dr. Bernstein, of Bioethics Discussion Blog:
I thought you might find this excerpt from New England Journal of Medicine Feb.5 2004 "Occam's Razor versus Saint's Triad" by Anthony A. Hilliard, M.D, et. al., appropriate to your recent patient challenge for a valid diagnosis. I have described these two approaches to diagnosis to my second year medical students. My view is to begin with Occam's Razor but if the facts of the case don't fit together then discard Occam and think seriously about Saint. ..

“What on earth is Saint’s Triad?” So asked C.F.M. Saint several decades ago about his own eponym. Saint, a South African surgeon, emphasized the importanceof considering the possibility of multiple separate diseases in a patient whenever his or her history and the results of the physical examinationwere atypical of any single condition.

The triad that bears his name is the association of hiatal hernia, gallbladder disease, and diverticulosis. There is no pathophysiological basis for the coexistence of these three diseases; that, perhaps, was his point. Saint emphasized that more than one disease may be responsible for a patient’s clinical signs and symptoms.
This is, in fact, the same point made by the apocryphal Hickam, credited with Hickam’s dictum: “A patient can have as many diagnoses as he darn well pleases.”

Because physicians are seeing an increasing number of patients with a multitude of
acute and chronic illnesses, the views of Saint and Hickam warrant consideration in the practice of modern medicine. Neither name, however, is as well known as that of William Osler, who is credited with applying the teaching of Occam to clinical medicine. (Note: see Cheerful Oncologist for more about Osler.)

In the 14th century, William of Occam stated, “Plurality must not be posited without necessity.” A subsequent version of this statement was expressed as “Among competing hypotheses, favor the simplest one” — hence the term “Occam’s razor.” ...parsimony of diagnosis is an important standard in modern medicine; however this principle can fail us. As the population continues to age — and as diagnostic studies increase in number and sophistication — the dulling of Occam’s razor is certain to continue.


I was going to "live-blog" January 24, supposedly "the most depressing day of the year" (has Saint Nate started his "Carnival of the Skeptical" yet?). But the day turned out so well here! Sunny, brilliant, 54 degrees. We've had no snow, and hardly any rain this year (I'm afraid that our annual drenching has gone east and turned to blizzards.) We've had some fog, but it doesn't last long. We even found new, pink buds on our daphne yesterday. Has that ever happened in January?
Nothing grim to report from Eugene, at least not yet...
Click for Eugene, Oregon Forecast