Not all hospitals are created equal, and the differences in quality can be a matter of life or death. In the first comprehensive study comparing how well individual hospitals treated a variety of medical conditions, researchers found that patients at the worst American hospitals were three times more likely to die and 13 times more likely to have medical complications than if they visited one of the best hospitals.

The study, published Wednesday in the academic journal PLOS One, shows “there is considerable variation in outcomes that really matter to patients, from hospital to hospital, as well as region to region,” said Dr. Thomas H. Lee, a longtime health care executive who was not involved in the research.