The fourth annual study identifying the top U.S. health systems was released yesterday by Thomson Reuters, which culled data from more than 300 organizations and singled out 15 hospital systems that achieved superior clinical outcomes based on a composite score of eight measures of quality, patient perception of care and efficiency.

"Health system performance is beginning to reflect aspirations to provide more consistent outcomes across communities served," says Jean Chenoweth, senior vice president for performance improvement and 100 Top Hospitals program at Thomson Reuters.  "Health care reform appears to have stimulated the increased rate of improvement at the system level."

The study found that the top 15 health systems held post-discharge 30 day mortality rates steady, while poor health systems demonstrated a significant increase in post discharge mortality. Winning hospitals also had 17% fewer deaths than expected considering patient severity, while non-winning hospitals had 4% more deaths than expected.

In addition to better mortality rates, the best health systems had shorter hospital stays with an average stay of 4.7 days, nearly half a day shorter than their peers' median of 5.1 days. There was also better patient safety and core measure adherence: Top health systems had 23% fewer adverse patient safety events than expected and had better adherence to core measures of care than their peers

The study divides the top health systems into three comparison groups based on total operating expense of the member hospitals.  Top winners in the large health system category (more than $1.5 billion total operating expense) were: Banner Health, Phoenix, Ariz.; CareGroup Healthcare System, Boston, Mass.; Jefferson Health System, Radnor, Pa.; Memorial Hermann Healthcare System, Houston, Texas; and St. Vincent Health, Indianapolis, Ind. Medium health systems ($750 million-$1.5 billion) were:  Baystate Health, Springfield, Mass.; Geisinger Health System, Danville, Pa.; HCA Central and West Texas Division, Austin, Texas; Mission Health System, Asheville, N.C.; and Prime Healthcare Services, Ontario, Canada.