Let’s say you run a grocery store. One of many problems you’ll face is what to tell your employees about managing food close to expiration. One option is to give them a set of rules (e.g. all fruit is thrown away after three days). Another option is to give them discretion (e.g. look carefully at the fruit after three days, but use your judgment when it comes to deciding what to throw away). The tradeoffs are clear: The rule approach means you’ll lose more fruit, but the discretion approach means there will sometimes be rotting fruit in the mix if your employees don’t do a good job.
This is a classic decision problem that comes up all the time. And it is perhaps nowhere more important than in medical decision-making.
Rule-based decision-making — for example, about treatment or testing — is extremely common in medicine. If you’re pregnant, for instance, the rules change the moment you cross into being over 35 rather than under 35. More tests, monitoring and concern go into the 35-years-and-one-month-old pregnant woman than the 34-years-and-11-months-old woman. Or consider prostate cancer screening: Decisions about whether to do a biopsy are often made based on a cutoff. A prostate-specific antigen (PSA) level of 4.1 warrants testing, but a level of 3.9 does not.
Virtually everyone would agree that having some rule-type guidelines like these to inform decision-making is useful. But most people would also probably agree that, especially in medicine, some discretion is valuable. A pregnant 34-year-old who has had two miscarriages should probably be considered higher risk than a 35-year-old with two healthy previous pregnancies. Doctors are highly trained, and there’s good reason to think they should use some discretion when treating patients.
One of the starkest examples of reliance on rules in medicine comes from studying infant mortality. Keep reading