[guan]

It's still an information asymmetry story. From my cursory reading, the contribution is to identify what kind of information asymmetry is involved in healthcare, namely that it's more about the cost of treatment than about the probability of illness.

I know that health insurance is often used to teach asymmetric information models, but it wasn't always obvious that it's a good example. Someone selling a used car might know a lot more about the car's hidden costs than anyone else, but does the typical buyer of health insurance really know more about his or her probability of illness than a sophisticated insurer with good doctors and actuaries and a lot of data?

This led some economists to argue that the problem in health insurance markets is not asymmetric information, but rather too much information—the insurer already knows you will be a bad risk. This research makes it clear that there really is asymmetric information and spells out what it is.