The 1999 Institute of Medicine Report  concluded that from 44,000 to 98,000 people die annually due to errors in inpatient hospital treatment. The Insitiute of Medicine report prompted hundreds of media citations.

      According to Dr. Lucien Leape, lead the author of the Harvard study, the number of deaths from medical errors in hospitals account for the equivalent to the death toll from three jumbo jet crashes every two days. Public Health Reports, 1999; 114: 302-317    July / August, 1999.  One in every 10 patients admitted to a hospital is the victim of at least one mistake. National Public Radio (NPR) November 21, 2000, (Audio)

   Only 1.53 percent of patients who were harmed by medical treatment filed malpractice claims.
                 N Engl J Med 1989 Aug 17;321(7):480-4

     The I.O.M. based its conclusion on two reviews of hospital charts from New York (1984) and Colorado/Utah (1992).

    In 1991, the Harvard School of Public Health studied 1984 data from 51 New York hospitals found that 3.7 % of hospital admissions had an edverse event due to medical error and 13.6 % of those errors resulted in death. A similar study of hospitals in Utah and Colorado found 2.9 % of hospital admissions had an adverse event due to medical error and 6.6 % of those errors resulted in death. Extrapolating to the number of hospital admissions in 1997 (33,600,000), the IOM arrived at the highly cited estimates for the upper and lower bounds for deaths due to hospital errors.

     The complete text of the Insitiute of Medicine study is available online:
To Err Is Human: Building a Safer Health System    Linda T. Kohn, Janet M. Corrigan, and Molla S. Donaldson, Editors

How Many Errors, What Kinds of Errors, Not Following Guidelines,
 Wrong Side Surgery & other errors , Reducing Errors, M.D. Discipline