Hawai'i ranked below average in a study of hospitals nationally, placing among the bottom six states in terms of risk-adjusted mortality rates.

The HealthGrades Hospital Quality in America study found Hawai'i tied with Idaho in an evaluation of in-hospital mortality and complication rates. The study examined Medicare patient data from 15 hospitals in Hawai'i but did not identify them.

It was the 12th year for the study by HealthGrades, a health care ratings company that operates Web sites where people can look up individual hospital ratings, along with those of physicians and nursing homes. The report was the result of looking at patient outcomes at 5,000 non-federal hospitals.

Overall, it found that patients had an almost 52 percent lower chance of dying in a top-rated hospital compared with the average U.S. hospital.

To compare states, it looked at eight general categories, ranging from cardiac surgery to stroke care. Hawai'i hospitals improved in risk-adjusted mortality or death rates in each category, though reported a worse performance than in 2006 in terms of critical care.

The mortality rates were aggregated to come up with a combined rate for states. Hawai'i's combined risk-adjusted mortality rate was 7.49 percent; the national average was 6.09 percent.

The 2008 rate was an improvement from 2006, when Hawai'i's combined rate was 8.3 percent.

The report found that 11 of the hospitals it researched here in 2008 had average performance, falling into a group with 70 percent of the medical centers studied. None of the local hospitals made the top 15 percent nationally, while four fell into the bottom 15 percent.

The report is available through the www.HealthGrades.com Web site.