Sunday, October 17, 2010

Magic By Numbers

I have such high expectations from the NY Times that I always feel betrayed when they print garbage.

In today's Sunday issue, Harvard psychology professor and TV personality Daniel Gilbert penned an editorial titled “Magic by Numbers: Why a Roman Emperor is responsible for the 7-day antibiotic course.” Gilbert asserts that because human beings are irrationally drawn to use certain numbers relating to our 10 fingers and 7x24 calendars, medical therapies are now polluted with these numbers rather than numbers with scientific merit.

He bases his findings on a compelling plethora of evidence: 1) his own ruminations; 2) a flawed understanding of history;  3) a handful of anecdotes; and 4) completely uninformed speculation of how prescriptions are formulated.

The whole idea came to him because a doctor had prescribed a 7 day course of anti-biotics.

“Why not six, eight, or nine-and-a-half? Did the number seven correspond to some biological fact about the human digestive tract or the life cycle of bacteria?
My doctor seemed smart. She probably went to one of the nation’s finest medical schools, and regardless of where she trained, she certainly knew more about medicine than I did. And yet, as I walked out of the ER that night with my prescription in hand, I couldn’t help but suspect that I’d just been treated with magic.”

Gilbert goes on to assert that people tend to use the number 7 because a Roman emperor coined the 7 day week. (My 11 year old recently taught me that the Neo-Babylonians invented the 7 day week in the 6th century BC – which simply points to Gilbert’s allergy to research.) Therefore that must be why antibiotics are prescribed for exactly 7 days.

He backs up his evidence for "magic numbers" with anecdotes of how people sometimes round off numbers to the nearest ten or five. But is that really such an amazing discovery of the human psyche -- that we choose to call someone back in 20 minutes rather than 17? Rounding numbers is a practical technique for remembering and tracking quantities. In no way does it imply that doctors must be plagiarizing from their calendars.

In fact, if Gilbert had simply asked his very smart, educated doctor, she could have explained that Yes, seven days does correspond to biological facts! Clinical studies clearly show that for this particular drug, six days is not always enough, and eight days is almost never needed. Why not 6.8, or 7.2? That’s easy – rounding off numbers when it comes to prescriptions improves patient compliance, a health benefit that far outweighs the fine tuning of a decimal place.

Further, Gilbert could have learned through a simple Google query that in fact there are just as many meds prescribed for 5, 6 or 8 days. Fortunately, Gilbert ignored these irrelevant facts by declining to ever collect them. 

This ability to infer patterns from incomplete anecdotes must somewhere violate a business process patent owned by Malcom Gladwell. Indeed I had to check the byline to see if this was another brilliant Gladwell phenomenon. And then I saw the web site for Gilbert's book touting him as the next Gladwell! (Coincidentally, just yesterday I read about Gilbert's book on finding happiness-- it's a target of this month's Skeptic Magazine cover story debunking the happiness craze.)

But 7 isn’t the only magic number, writes Gilbert. He speculates that his antibiotics are prescribed 3 times per day because 3 implies a beginning, middle and end. (Really.) Again, a doctor could have explained to him about the timing of chemical breakdowns, and the compliance benefits of prescribing meds every morning, every morning/night, or at every meal.

But not just 7 and 3. According to Gilbert, nine is also a magic number as evidenced by all the prices that end in 99 cents.

But not just 3, 7 and 9. Four and six are magic, too, because they have soft-sounding syllables. (Really.)

And of course 5 and 10 are magic because they correspond to the fingers on our hands.

But that’s it. Those are the only “magic numbers” that everyone likes. 3, 4, 5, 6, 7, 9 and 10. (He might be discouraged to learn that no one read his editorial because it appeared on page 8.)

Oh, and also 12, because it “corresponds to a half turn of our planet.” But that’s all. 

The good news here is that Gilbert has just provided us forever with the canonical example of Pop Psychology. But that's just my 2 cents.

1 comment:

  1. As usual with pseudo-science mythology, there's a grain of truth here.

    When antibiotics were first invented, clinical trials had not yet been. So the first therapists picked a number and gave the drugs for that long and, voila, it worked.

    Much of our "treatment regimen" comes from this empiric, non-scientific, historical usage. So, a week, ten days, two weeks, etc. No one was checking bacterial load--it was all about seeing if the patient got better.

    When I was in med school in the 80s (yes, I'm getting old), there was a huge push to go back and actually check and see if these regimens had any scientific validity. During the course of my training, the treatment for uncomplicated UTIs went from 10 days, to 7, to 3, to single-dose therapy.

    New antibiotics are far better studied--so therapeutic regimens are by definition based on patient studies rather than, "here, try this for 10 days."

    How many times a day you take something, though, has never been empirical or haphazard. The idea that 3 represents a magic number to docs is horsehocky--drug levels wear off as the medicine gets metabolized. In the old days it was determined by recurrence of fever; now we have assays.

    And biochemistry. We tinker with the molecules and delivery systems to aim for slower metabolism, since patients are far more compliant with once a day dosing.

    So, a grain of truth. But tons of fiction. Like just about everything you read on the web.