A major focus of the healthcare law signed by Governor Deval Patrick last week is that doctors should be paid for keeping patients healthy rather than for the volume of tests or treatments they order. Yet, several recent publications question whether pay-for-performance systems actually lead to better care for patients. A review of seven studies of primary care programs that paid doctors extra for meeting certain targets, published by the Cochrane Collaboration in September, was inconclusive about the effect on quality of care. "Implementation should proceed with caution," the authors wrote.