Friday, August 14, 2009

The Bell Curve

I was browsing through the 4th edition of Intermediate Physics for Medicine and Biology the other day (I do this sometimes; don’t ask why), and I noticed the footnote at the bottom of page 566 in Appendix H: The Binomial Probability Distribution, which states
See also A. Gawande, The bell curve. The New Yorker, December 6, 2004, pp. 82–91.
I thought to myself, “that must be one of the changes Russ Hobbie made when we were preparing the 4th edition, because I don’t remember ever reading the article.” Well, if Russ recommends it, then I want to read it, so I found the article on the web. It turns out to be a lovely, well-written piece about cystic fibrosis (CF), modern medicine, self-evaluation, and striving for excellence. The excerpt below is the one Russ probably had in mind when he added the citation of the article to our book. It describes a discussion between a teenage CF patient, Janelle, her physician Dr. Warwick, and the article’s author Atul Gawande, who is a surgeon and was observing Janelle’s interview as part of an effort to improve cystic fibrosis care. In the quote below, Janelle’s doctor is speaking.
“Let’s look at the numbers,” he said to me, ignoring Janelle. He went to a little blackboard he had on the wall. It appeared to be well used. “A person’s daily risk of getting a bad lung illness with CF is 0.5 per cent.” He wrote the number down. Janelle rolled her eyes. She began tapping her foot. “The daily risk of getting a bad lung illness with CF plus treatment is 0.05 per cent,” he went on, and he wrote that number down. “So when you experiment you’re looking at the difference between a 99.95-per-cent chance of staying well and a 99.5-per-cent chance of staying well. Seems hardly any difference, right? On any given day, you have basically a one-hundred-per-cent chance of being well. But”—he paused and took a step toward me—“it is a big difference.” He chalked out the calculations. “Sum it up over a year, and it is the difference between an eighty-three-per-cent chance of making it through 2004 without getting sick and only a sixteen-per-cent chance.
He turned to Janelle. “How do you stay well all your life? How do you become a geriatric patient?” he asked her. Her foot finally stopped tapping. “I can’t promise you anything. I can only tell you the odds.”
In this short speech was the core of Warwick’s world view. He believed that excellence came from seeing, on a daily basis, the difference between being 99.5-per-cent successful and being 99.95-per-cent successful. Many activities are like that, of course: catching fly balls, manufacturing microchips, delivering overnight packages. Medicine’s only distinction is that lives are lost in those slim margins.
The article describes how one CF center began measuring its own success against the top programs in the country, and their efforts to improve. Gawande concludes
The hardest question for anyone who takes responsibility for what he or she does is, What if I turn out to be average? If we took all the surgeons at my level of experience, compared our results, and found that I am one of the worst, the answer would be easy: I’d turn in my scalpel. But what if I were a C? Working as I do in a city that’s mobbed with surgeons, how could I justify putting patients under the knife? I could tell myself, Someone’s got to be average. If the bell curve is a fact, then so is the reality that most doctors are going to be average. There is no shame in being one of them, right?
Except, of course, there is. Somehow, what troubles people isn’t so much being average as settling for it. Everyone knows that averageness is, for most of us, our fate. And in certain matters—looks, money, tennis—we would do well to accept this. But in your surgeon, your child’s pediatrician, your police department, your local high school? When the stakes are our lives and the lives of our children, we expect averageness to be resisted. And so I push to make myself the best. If I’m not the best already, I believe wholeheartedly that I will be. And you expect that of me, too. Whatever the next round of numbers may say.

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