Four Cleveland-area hospitals made HealthGrades' "America's 50 Best Hospitals 2011" list: Summa Akron City and St. Thomas Hospitals, Akron General Medical Center, Marymount Hospital, and Hillcrest Hospital.

The rankings were based on an analysis of more than 140 million Medicare patient records over an 11-year time period.

"To be recognized with this elite distinction, hospitals must have had risk-adjusted mortality and complication rates that were in the top 5% in the nation for the most consecutive years. On average, patients treated at America's 50 Best Hospitals had a nearly 30% lower risk of death and 3% lower rate of complications," the article states.

If all hospitals in the U.S. had performed at this level, more than a half-million Medicare deaths could have been prevented in the last decade.

Read the entire diagnosis here.