Medical malpractice is a national epidemic. Mistakes made by medical personnel contribute to the deaths of between 210,000 and 440,000 patients each year, according to a study published in the Journal of Patient Safety. By that estimate, medical malpractice is the third leading cause of death in the United States, behind only heart disease and cancer.

A recent study has identified the most deadly type of medical malpractice: diagnostic errors.
According to research published in the journal BMJ Quality and Safety, diagnostic mistakes are the most common, dangerous and costly category of medical errors, causing permanent injury to, or death of, up to 160,000 patients in the U.S. each year.

Johns Hopkins University researchers examined 25 years worth of medical malpractice cases, including more than 350,000 claims. Diagnostic errors, which include incorrect, missed or delayed diagnoses, accounted for almost 29 percent of claims, more than other types of medical errors, such as medication, surgery or treatment mistakes. Diagnostic errors also accounted for the largest cost: $38.8 billion from 1986 to 2010, or 35.2 percent of total payments. More than 40 percent of the diagnostic errors examined resulted in death.

Researchers said that an essential factor in reducing medical mistakes is improving monitoring and measuring of errors. Diagnostic errors are not measured or reported by the federal government or private quality programs. According to David Newman-Toker, an associate professor of neurology at Johns Hopkins and the lead author of the study, “No one wants to tell anyone they are missing 10 percent to 20 percent of their diagnoses.”

The Johns Hopkins study used data from the National Practitioner Data Bank, which is an electronic repository of all medical malpractice payments, to arrive at an estimate of 160,000 diagnostic errors per year, and “it is probably a lot higher than that,” said Newman-Toker.