Does Greater Volume = Higher Quality?
Not necessarily. As we have observed often at this site, pay-for-performance begins with the claim that we should pay more for better outcomes and after sleight-of-the-hand often ends by paying more, not for better outcomes, but for someone's notion of what the correct inputs should be. The latest depressing example is in the field of bariatric surgery ( e.g., stomach staples ):
The notion of designating bariatric surgery centers of excellence was promoted by the Centers for Medicare and Medicaid Services in 2006. The American College of Surgeons and the American Society for Metabolic and Bariatric Surgery established guidelines to designate them.
[However,] patients undergoing bariatric surgery have similar outcomes whether the operation occurs at a so-called "center of excellence" or in a regular hospital, researchers found.
The researchers said the findings show that the government's minimum volume for designation as a center of excellence — 125 operations per year — "does not necessarily result in better outcomes and that the minimum volume requirement is not evidenced-based."
This illustrates why you don’t want to subject doctors and hospitals to cookbook medicine. An association that is generally true (greater volume = safer surgery) may not always be true. Markets, not cookbooks should guide medical proctice.
Interesting and surprising finding.
This is part of the larger problem of trying to judge quality by looking at inputs rather than outputs.
Someone observes a positive relationship between an input and an output. Then the bean counters decide that the input IS quality.