“Pay for performance” is one of those slogans that seem to upset no one. To most people it’s a no-brainer that we should pay for quality and not quantity. We all know that paying doctors based on the amount of care they provide, as we do with a traditional fee-for-service setup, creates incentives for them to give more care. It leads to increased health care spending. Changing the payment structure to pay them for achieving goals instead should reduce wasteful spending.

So it’s no surprise that pay for performance has been an important part of recent reform efforts. But in reality we’re seeing disappointingly mixed results. Sometimes it’s because providers don’t change the way they practice medicine; sometimes it’s because even when they do, outcomes don’t really improve.

The idea behind pay for performance is simple. We will give providers more money for achieving a goal. The goal can be defined in various ways, but at its heart, we want to see the system hit some target. This could be a certain number of patients receiving preventive care, a certain percentage of people whose chronic disease is being properly managed or even a certain number of people avoiding a bad outcome. Providers who reach these targets earn more money.

The problem, one I’ve noted before, is that changing physician behavior is hard. Sure, it’s possible to find a study in the medical literature that shows that pay for performance worked in some small way here or there. For instance, a study published last fall found that paying doctors $200 more per patient for hitting certain performance criteria resulted in improvements in care. It found that the rate of recommendations for aspirin or for prescriptions for medications to prevent clotting for people who needed it increased 6 percent in clinics without pay for performance but 12 percent in clinics with it.