The best studies we have that investigate the severity of the problem of medical error and medical malpractice conclude that it is both wide ranging and underreported.
The numbers of deaths attributable to medical error has been increasing in the last 20 or so years, mostly because of a renewed effort to properly categorize the causes of death. As early as 1999, an Institute of Medicine study (“To Err Is Human”) had concluded that “at least 44,000 and perhaps as many as 98,000 Americans die in hospitals each year as a result of medical errors.”
A later study in 2010 found almost twice that many deaths, at 180,000. Following on that, a 2013 study suggested the numbers range from 210,000–440,000 deaths per year attributable to medical malpractice.
Most recently, a bombshell report from Johns Hopkins University in 2016 argued that medical errors may be responsible for over 250,000 deaths each year, making medical error the third leading cause of death in the U.S.