America's Best Hospitals: Here's How We Selected Them

This is Year 20 for America's Best Hospitals, a tool for patients who need medical sophistication that most facilities are unable to provide. We don't grade hospitals, as other ratings and rankings do, on routine procedures like outpatient hernia repair or manageable conditions like low-grade heart failure. We look instead at how well these institutions do in complex and demanding situations—replacing an 85-year-old's heart valve, diagnosing and treating a spinal tumor, and dealing with inflammatory bowel disease, to name three examples. High-stakes medicine calls for more than the usual brand of doctoring.

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We ranked hospitals in 16 specialties, from cancer and heart disease to respiratory disorders and urology. A total of 4,861 hospitals were put through the statistical wringer. (Certain facilities, such as prison hospitals and military installations, were excluded because of unavailable data, a very small number of beds, or other factors that made evaluation difficult or pointless.)

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Only 174 hospitals scored high enough to be ranked in even one of the 16 specialties. And of these, just 21 qualified for our Honor Roll by ranking at or near the top in at least six specialties.

Hard data, such as death rates and numbers of nurses, largely determined 12 of the 16 specialty rankings. To be a candidate for these specialties, a hospital first had to meet any one of three criteria: be a teaching hospital, have at least 200 beds, or have at least 100 beds and at least four out of eight important medical technologies, such as current-generation CT scanners and precision radiation therapies. This year, 44 percent of all hospitals met that test.

Hospitals that passed that test next had to show a minimum number of Medicare inpatient discharges for certain procedures and conditions in 2005, 2006, and 2007. The number varied by specialty—325 in cancer, for example. Or they had to have been nominated by at least one physician in U.S. News surveys in 2007, 2008, and 2009.

The 1,859 hospitals left received a U.S. News Score from 0 to 100, based on reputation, death rate, patient safety, and care-related factors such as nursing and patient services. The 50 highest scorers are ranked. (Scores and complete data for the rest are also provided.) The details:

Reputation counted as 32.5 percent of the score. Each year we draw a random sample of 200 physicians from a national database for each of 12 specialties. They are asked to list five hospitals they consider among the best in their specialty for difficult cases, without taking into account cost or location. The figure shown for "reputation" in the rankings is the total percentage of the specialists in 2007, 2008, and 2009 who named the hospital in their response.

A mortality index made up 32.5 percent of the score. It indicates a hospital's ability to keep patients alive. Taking into account Medicare inpatients with certain conditions, it represents a comparison of the number of deaths within 30 days of admission in 2005, 2006, and 2007 with the number of deaths that would have been expected given the severity of each patient's illness. An index number above 1.00 means the hospital did worse than expected; below 1.00, better than expected. A program used by many hospitals and researchers called the 3M Health Information Systems APR-DRG made adjustments to the index according to the severity of each patient's condition.

A new patient safety index comprised 5 percent of the score. It shows how well a hospital minimizes harm to patients. Two of the seven index items, for example, are deaths of patients whose conditions should not have put them at significant risk, and incisions that reopen after surgery.

Other care-related factors, 30 percent of the score. Includes nurse staffing, technology, and other care-related information. The primary source was the American Hospital Association's 2007 survey of member and nonmember hospitals.

Another safety-associated change this year is that hospitals now receive credit for employing staff intensivists—physicians with special expertise in caring for patients in intensive care.

In the four remaining specialties—ophthalmology, psychiatry, rehabilitation, and rheumatology—hospitals were ranked on reputation alone, because so few patients die that mortality data mean little. As in the other 12 specialties, we surveyed specialists and used their responses for the most recent three years. Ranked hospitals were cited by at least 3 percent of the responding physicians.

The 2009 rankings were produced by RTI International, a leading research organization based in Research Triangle Park, N.C.