Medicare beneficiaries on average have a 71% lower chance of dying at one of the nation’s highest-rated hospitals compared with those treated at the lowest-rated hospitals, according to the annual HealthGrades Hospital Quality in America Study.

More than 266,000 Medicare lives could have been saved between 2004 and 2006, according to HealthGrades, which analyzes the wide variation in the quality of care between the highest-performing hospitals and all others.

But mortality rates have improved in America’s hospitals, with America’s top hospitals moving at a faster rate, the report said. Out of 18 medical procedures and conditions studied, pancreatitis, pulmonary embolism, diabetic acidosis and coma showed the largest decrease in mortality rates, according to the report. The smallest drop in mortality rates was associated with resection/replacement of the abdominal aorta, coronary procedures and heart attack treatments.