A study published in Health Services Research compared about 2,800 hospitals in the program with about 300 exempt from it. The study found no effect from financial incentives of the program on quality of care or patient satisfaction. But the study included data only up to nine months after the program’s start, and it may take hospitals longer to make measurable changes.

Another study, published in BMJ, looked at outcomes two and a half years after the start of the Hospital Value-Based Purchasing Program. It found no differences in changes in mortality rates between hospitals in the program versus those exempt from it. And another study, published in Health Affairs, found no evidence that the program improved patient satisfaction up to three years after implementation.

Jose Figueroa, a physician at Brigham and Women’s Hospital in Boston, and an assistant professor of medicine at Harvard Medical School, was an author of both of these longer studies. “So far, there’s no evidence the program has improved quality or patient satisfaction,” he said. He ticked off some possible reasons: “The financial incentives are too weak to drive any meaningful changes across hospitals. The program’s design, with numerous measures across different domains, makes it hard for hospitals to understand what to focus on.”

Medicare has achieved greater success with programs that have raised the stakes — ones that have put hospitals and health care organizations at greater risk of financial loss or have offered prospects for larger financial gain.

One popular approach, called “bundled payments,” pays health providers one amount for all of the care for a certain condition within a certain period — like 90 days for hip replacement care. There is evidence that some of these programs can save money without reductions in quality, although design details matter.

“Bundled payments are a straightforward way to make hospitals consider all the costs they are responsible for,” said Adam Sacarny, assistant professor with Columbia’s Mailman School of Public Health. “The evidence suggests they encourage hospitals to treat patients more efficiently, although the cost savings are at least partly offset by extra payments to hospitals to reward them for saving money in the first place.”

Another approach — accountable care organizations — also takes many forms. What they have in common is they offer health care organizations the chance to earn bonuses for accepting some financial risk, provided they meet a set of quality targets. Many studies of accountable care organizations (A.C.O.s) have found they reduce spending with no quality degradation.