A key component of children's hospital ratings may be statistically unreliable, fueling concerns over popular rankings used by millions of Americans every year, according to a new study. Researchers found that death rates across hospitals, which carry heavy weight in commercial rankings like the U.S. News & World Report Best Hospitals, are mostly indistinguishable from a statistical point of view. "It's like taking a stack of cards and shuffling them almost at random to put them in a rank order," said Chris Feudtner, MD, of The Children's Hospital of Philadelphia, whose findings appear in the journal Pediatrics. "You are chasing after something that is being buffeted around by chance," he told Reuters Health. Hospital death rates have become an increasingly popular yardstick for the quality of care that patients receive around the country and have been made publicly available by the Department of Health and Human Services.