The lede:

The idea of paying physicians more for providing guideline-based care has taken the American health system by storm in the last decade. Today, more than 150 pay-for-performance programs are centered on the notion that rewarding evidence-based care is key to improving health care quality.

But research shows there is a fundamental problem with the P4P programs: They have had little to no impact on quality. That is the conclusion of many studies, including a new analysis of quality incentives, published in the July/August Health Affairs. It compared 81 Massachusetts physician groups eligible for quality incentives with 73 that were not.

The whole shebang.