Which Illinois hospitals are the best? The worst? Depends on whom you ask.

Chicago Tribune (IL)

May 15-- May 15--Hospital grades, rankings and ratings are supposed to make it easier to choose where to get care.

But when more than half a dozen organizations regularly chime in, it can get a bit confusing for patients.

The nonprofit Leapfrog Group just released its latest patient safety grades Wednesday, dinging five Illinois hospitals with Ds and awarding 42 with As -- grades that Leapfrog says can mean the difference between life and death for some patients.

Other groups, however, rate hospitals differently. Each group has its own timing, methodology and intended audience. Here are some of the major groups that regularly evaluate hospitals, how they do it and who wins and loses under the systems.

Leapfrog Group

This nonprofit, founded by large employers and others who purchase health insurance plans, grades hospitals twice a year.

The grades are based on 28 measures of safety, including hand hygiene, bedsores and falls. The group gets the data from the federal Centers for Medicare and Medicaid Services as well as voluntary surveys sent to hospitals. Filling out the surveys can help hospitals, in some cases, score better grades, said Leah Binder, president and CEO of Leapfrog.

One local hospital that's fared particularly well under Leapfrog's ratings is the University of Chicago Medical Center, which has scored As from Leapfrog 15 times in a row. Other Chicago powerhouse hospitals, however, such as Loyola University Medical Center in Maywood, Northwestern Memorial Hospital and Rush University Medical Center haven't done as well, most recently earning Bs.

Go here to see full ratings.

U.S. News and World Report

Among other rankings, U.S. News and World Report releases lists of the best hospitals in the state and country each year. Hospitals are ranked on a number of factors, including survival and readmission rates, patient experience, patient safety and nursing quality, among other things.

Under this ratings system, Northwestern Memorial has been named the No. 1 hospital in the state for seven years in a row.

Last year, Rush University Medical Center ranked second, Loyola University Medical Center ranked third, and University of Chicago Medical Center and Advocate Christ Medical Center in Oak Lawn tied for fourth.

To see the lists, go here.

Medicare's Hospital Compare

This federal ratings system awards hospitals up to five stars for safety and quality -- but it has drawn ire from hospitals in recent years over its methodology.

The American Hospital Association has said the system penalizes hospitals in poor areas, where more patients might need to be readmitted because they don't have adequate resources to aid in their recovery at home. It also tends to give academic medical centers lower marks because they treat more complex patients than other hospitals, the association has argued.

Earlier this year, the system, run by the federal Centers for Medicare & Medicaid Services, gave University of Chicago and Loyola University medical centers only two out of five stars. Northwestern Memorial earned three out of five stars, and Rush got four stars.

Other Chicago area hospitals, however, got five out of five stars, including Amita Health Adventist Medical Center Hinsdale, Amita Health Saints Mary and Elizabeth Medical Center Chicago and Advocate Lutheran General Hospital in Park Ridge.

The federal agency proposed a number of additional changes to the methodology in February.

To search for hospital ratings go here.

IBM Watson Health

Each year, IBM Watson Health (yes, that IBM) releases a list of its 100 Top Hospitals. This was formerly known as the Truven Health Analytics 100 Top Hospitals.

The company bases its list on a variety of measures, including survival rates, complications, infections, length of stay, emergency department wait times, inpatients expenses, profit margins and patient satisfaction.

None of Chicago's biggest-name hospitals made this list this year. Illinois hospitals that made the cut most recently include Advocate Illinois Masonic Medical Center, NorthShore University HealthSystem's Evanston Hospital, Riverside Medical Center in Kankakee, Advocate Sherman Hospital in Elgin, Northwestern Medicine Central DuPage Hospital in Winfield and Northwestern Medicine Delnor Hospital in Geneva.