The first question healthcare providers should ask themselves is “why is it important to learn about ADRs?”  The answer is “because ADRs are one of the leading causes of morbidity and mortality in health care”.  The Institute of Medicine reported in January of 2000 that from 44,000 to 98,000 deaths occur annually from medical errors.{Committee}  Of this total, an estimated 7,000 deaths occur due to ADRs.  To put this in perspective, consider that 6,000 Americans die each year from workplace injuries.
However, other studies conducted on hospitalized patient populations have placed much higher estimates on the overall incidence of serious ADRs.  These studies estimate that 6.7% of hospitalized patients have a serious adverse drug reaction with a fatality rate of 0.32%.{Lazarou}  If these estimates are correct, then there are more than 2,216,000 serious ADRs in hospitalized patients, causing over 106,000 deaths annually.  If true, then  ADRs are the 4th leading cause of death -- ahead of pulmonary disease, diabetes, AIDS, pneumonia, accidents, and automobile deaths.
These statistics do not include the number of ADRs  that occur in ambulatory settings.  Also, it is estimated that over 350,000 ADRs occur in U.S. nursing homes each year.{Gurwitz}  The exact number of ADRs is not certain and is limited by methodological considerations.  However, whatever the true number is, ADRs represent a significant public health problem that is, for the most part, preventable.
Committee on Quality of Health Care in America: Institute of Medicine. To err is human: building a safer health system. Washington, D.C.: National Academy Press, 2000.
Lazarou J, Pomeranz B, Corey PN. Incidence of adverse drug reactions in hospitalized patients: A meta-analysis of prospective studies. JAMA 1998; 279:1200-1205.
Gurwitz JH, Field TS, Avorn J, McCormick D, Jain S, Eckler M et al. Incidence and preventability of adverse drug events in nursing homes. Am J Med 2000; 109(2):87-94.