Superfreakonomics_ global cooling, patri - Steven D. Levitt [35]
The data also show which doctor treated which patients, and we know a good bit about each doctor as well, including age, gender, medical school attended, hospital where residency was served, and years of experience.
When most people think of ERs, they envision a steady stream of gunshot wounds and accident victims. In reality, dramatic incidents like these represent a tiny fraction of ER traffic and, because WHC has a separate Level I trauma center, such cases are especially rare in our ER data. That said, the main emergency room has an extraordinary array of patient complaints, from the life-threatening to the entirely imaginary.
On average, about 160 patients showed up each day. The busiest day is Monday, and weekend days are the slowest. (This is a good clue that many ailments aren’t so serious that they can’t wait until the weekend’s activities are over.) The peak hour is 11:00 A.M., which is five times busier than the slowest hour, which is 5:00 A.M. Six of every ten patients are female; the average age is forty-seven.
The first thing a patient does upon arrival is tell the triage nurse what’s wrong. Some complaints are common: “shortness of breath,” “chest pains,” “dehydration,” “flulike symptoms.” Others are far less so: “fish bone stuck in throat,” “hit over the head with book,” and a variety of bites, including a good number of dog bites (about 300) and insect or spider bites (200). Interestingly, there are more human bites (65) than rat bites and cat bites combined (30), including 1 instance of being “bitten by client at work.” (Alas, the intake form didn’t reveal the nature of this patient’s job.)
The vast majority of patients who come to the ER leave alive. Only 1 of every 250 patients dies within a week; 1 percent die within a month, and about 5 percent die within a year. But knowing whether a condition is life-threatening or not isn’t always obvious (especially to the patients themselves). Imagine you’re an ER doc with eight patients in the waiting room, one each with one of the following eight common complaints. Four of these conditions have a relatively high death rate while the other four are low. Can you tell which ones are which?
Here’s the answer, based on the likelihood of a patient dying within twelve months:*
Shortness of breath is by far the most common high-risk condition. (It is usually notated as “SOB,” so if someday you see that abbreviation on your chart, don’t think the doctor hates you.) To many patients, SOB might seem less scary than something like chest pains. But here’s what the data say:
So a patient with chest pains is no more likely than the average ER patient to die within a year, whereas shortness of breath more than doubles the death risk. Similarly, roughly 1 in 10 patients who show up with a clot, a fever, or an infection will be dead within a year; but if a patient is dizzy, is numb, or has a psychiatric condition, the risk of dying is only one-third as high.
With all this in mind, let’s get back to the question at hand: given all these data, how do we measure the efficacy of each doctor?
The most obvious course would be to simply look at the raw data for differences in patient outcomes across doctors. Indeed, this method would show radical differences among doctors. If these results were trustworthy, there would be few factors in your life as important as the identity of the doctor who happens to draw your case when you show up at the ER.
But for the same reasons you shouldn’t put much faith in doctor report cards, a comparison like this is highly deceptive. Two doctors in the same ER are likely to treat very different pools of patients. The average patient at noon, for instance, is about ten years older than one who comes in the middle of the night. Even two doctors working the same shift might see very different patients, based on their skills and interests. It is the triage nurse’s job to