Medical Errors

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Medical Errors

Introduction and definitions
Proposals for improvement
What patients can do

Introduction and definitions

The subject of medical errors is not a new one. However, it did not come to widespread attention in the United States until the 1990s, when government-sponsored research about the problem was undertaken by two physicians, Lucian Leape and David Bates. In 1999, a report compiled by the Committee on Quality of Health Care in America and published by the Institute of Medicine (IOM) made headlines with its findings. As a result of the IOM report, President Clinton asked the Quality Interagency Coordination Task Force (QuIC) to analyze the problem of medical errors and patient safety, and make recommendations for improvement. The Report to the President on Medical Errors was published in February 2000.

It is important to understand the terms used by the government and health care professionals in describing medical errors in order to distinguish between injury or death resulting from mistakes made by people on the one hand, and unfortunate results of treatment on the other. Some allergic reactions to medications or failures to respond to cancer treatment, for example, result from physical differences among patients or the known side effects of certain treatments, and not from prescribing the wrong drug or therapy for the patient’s condition. This type of negative outcome is called an adverse event in official documents. Adverse events can be defined as undesirable and unintentional, though not necessarily unexpected, results of medical treatment. An example of an adverse event is discomfort in an artificial joint that continues after the expected recovery period, or a chronic headache following a spinal tap.

A medical error, on the other hand, is an adverse event that could be prevented given the current state of medical knowledge. The QuIC task force expanded the IOM’s working definition of a medical error to cover as many types of mistakes as possible. Their definition of a medical error is as follows: “The failure of a planned action to be completed as intended or the use of a wrong plan to achieve an aim. Errors can include problems in practice, products, procedures, and systems.” The National Patient Safety Foundation (NPSF) prefers the term “healthcare error” to “medical error,” and defines such errors as follows: “An unintended healthcare outcome caused by a defect in the delivery of care to a patient. Healthcare errors may be errors of commission (doing the wrong thing), omission (not doing the right thing), or execution (doing the right thing incorrectly).” A useful brief definition of a medical error is that it is a preventable adverse event.


The statistics contained in the IOM report were startling. The authors of the report stated that between 45,000 and 98,000 Americans die each year as the result of medical errors. If the lower figure is used as an estimate, deaths in hospitals resulting from medical errors are the eighth leading cause of mortality in the United States, surpassing deaths attributable to motor vehicle accidents (43,458), breast cancer (42,297), and AIDS (16,516). Moreover, these figures refer only to hospitalized patients; they do not include people treated in outpatient clinics, ambulatory surgery centers, doctors’ or dentists’ offices, college or military health services, or nursing homes . Medical errors certainly occur outside hospitals; in 1999, the Massachusetts State Board of Registration in Pharmacy estimated that 2.4 million prescriptions are filled incorrectly each year in that state—which is only one of 50 states.

In terms of health-care costs, the IOM report estimated that medical errors cost the United States about $37.6 billion each year; about half this sum pays for direct health care.

Medical errors also carry a high psychological cost; according to a poll conducted by the National Patient Safety Foundation, 42% of the respondents had been affected personally by a medical error or had a friend or family member affected by one. The respondents rated the American health care system overall as only moderately safe, giving it a score of 4.9 on a 1-7 point scale, in which 7 was defined as very safe and 1 as very unsafe.


Adverse event— An undesirable and unintended result of a medical treatment or intervention.

Medical error— A preventable adverse event.

Systems analysis— An approach to medical errors and other management issues that looks for problems in the work process rather than singling out individuals as bad or incompetent.

The United States is not unique in having a high rate of medical errors. The United Kingdom, Australia, and Sweden are presently undertaking studies of their respective health-care systems. British experts estimate that 40,000 patients die each year in the United Kingdom as the result of medical errors. Australia has been testing a new system for reporting errors since 1995.


There is no single universally accepted method of classifying medical errors in order to describe them more fully. The 2000 QuIC report lists five different classification schemes that have been used:

  • type of health care given (medication, surgery, diagnostic imaging, etc.)
  • severity of the injury (minor discomfort, serious injury, death, etc.)
  • legal definitions (negligence, malpractice, etc.)
  • setting (hospital, emergency room, intensive care unit, nursing home, etc.)
  • persons involved (physician, nurse, pharmacist, patient, etc.)

The importance of these different ways to classify medical errors is their indication that different types of errors require different approaches to prevention and problem solving. For example, medication errors are often related to such communication problems as misspelled words or illegible handwriting, whereas surgical errors are often related to unclear or misinterpreted diagnostic images.

Causes of medical errors

The causes of medical errors are complex and not yet completely understood. Some causes that have been identified include the following:

  • Communication errors. One widely publicized case from 1994 involved the death of a Boston newspaper columnist from an overdose of chemotherapy for breast cancer due to misinterpretation of the doctor’s prescription; the patient was given four times the correct daily dose, when the doctor intended the dosage to be administered instead over a four-day period. Other cases involve medication mix-ups due to drugs with very similar names. The Food and Drug Administration (FDA) has identified no fewer than 600 pairs of look-alike or sound-alike drug names since 1992.
  • The increasing specialization and fragmentation of health care. The more people involved in a patient’s treatment, the greater the possibility that important information will be missing along the chain.
  • Human errors resulting from overwork and burnout. For some years, hospital interns, residents, and nurses have attributed many of the errors made in patient care to the long hours they are expected to work, many times with inadequate sleep. With the coming of managed care, many hospitals have cut the size of their nursing staff and require those that remain to work mandatory overtime shifts. A study published in the Journal of the American Medical Association in October 2002 found a clear correlation between higher-than-average rates of patient mortality and higher-than-average ratios of patients to nurses.
  • Manufacturing errors. Instances have been reported of blood products being mislabeled during the production process, resulting in patients being given transfusions of an incompatible blood type.
  • Equipment failure. A typical example of equipment failure might be intravenous pump with a malfunctioning valve, which would allow too much of the patient’s medication to be delivered over too short a time period.
  • Diagnostic errors. A misdiagnosed illness can lead the doctor to prescribe an inappropriate type of treatment. Errors in interpreting diagnostic imaging have resulted in surgeons operating on the wrong side of the patient’s body. Another common form of diagnostic error is failure to act on abnormal test results. As of 2006, studies of autopsies in the United States indicated that doctors misdiagnosed fatal illnesses about 20% of the time.
  • Poorly designed buildings and facilities. Hallways that end in sharp right angles, for example, increase the likelihood of falls or collisions between people on foot and patients being wheeled to an operating room.

Ways of thinking about medical errors

One subject that has been emphasized in recent reports on medical errors is the need to move away from a search for individual culprits to blame for medical errors. This judgmental approach has sometimes been called the “name, shame, and blame game.” It is characterized by the belief that medical errors result from inadequate training or from a few “bad apples” in the system. It is then assumed that medical errors can be reduced or eliminated by identifying the individuals at fault, and firing or disciplining them. The major drawback of this judgmental attitude is that it makes health-care workers hesitate to report errors for fear of losing their own jobs or fear of some other form of reprisal. As a result of underreporting, hospital managers and others concerned with patient safety often do not have an accurate picture of the frequency of occurrence of some types of medical errors.

Both the IOM report and the QuIC report urge the adoption of a model borrowed from industry that incorporates systems analysis. This model emphasizes making an entire system safer rather than punishing individuals; it assumes that most errors result from problems with procedures and work processes rather than bad or incompetent people; and it analyzes all parts of the system in order to improve them. The industrial model is sometimes referred to as the continuous quality improvement model (CQI). Hospitals that are implementing error-reduction programs based on the CQI model have found that a non-punitive procedure for reporting medical errors has improved morale among the staff as well as significantly reduced the number of medical errors. At Columbia-Presbyterian Hospital, for example, patients as well as staff can report medical errors via the Internet, a telephone hotline, or paper forms.

Proposals for improvement

Current proposals for reducing the rate of medical errors in the American health-care system include the following:

  • Adopt stricter standards of acceptable error rates. One reason that industrial manufacturers have made great strides in product safety and error reduction is their commitment to improving the quality of the work process itself.
  • Standardize medical equipment and build in mechanical safeguards against human error. Anesthesiology is the outstanding example of a medical specialty that has cut its error rate dramatically by asking medical equipment manufacturers to design ventilators with standardized controls and valves to prevent the oxygen content from falling below that of room air. These changes were the result of studies that showed that many medical errors resulted from doctors having to use unfamiliar ventilators and accidentally turning off the oxygen flow to the patient.
  • Improve the working conditions for nurses and other hospital staff. Recommendations in this area include redesigning hospital facilities to improve efficiency and minimize falls and other accidents, as well as reducing the length of nursing shifts below 12.5 hours. Since 2003, residency programs for physicians have been redesigned to lower the risk of medical errors caused by human fatigue. These changes resulted from rules imposed in July 2003 by the Accreditation Council for Graduate Medical Education (ACGME). The rules limit residents to an 80-hour work week and 24 continuous hours on call, and guarantee one day off each week.
  • Make use of new technology to improve accuracy in medication dosages and recording patients’ vital signs. Innovations in this field include giving nurses and residents handheld computers for recording patient data so that they do not have to rely on human memory for so many details. Another innovation that helped Veterans Administration (VA) hospitals cut the rate of medication errors was the introduction of a handheld wireless bar-coding system. After the system went into operation at the end of 1998, the number of medication errors in VA hospitals dropped by 70%.
  • Develop a nationwide database for error reporting and analysis. At present, there is no unified system for tracking different types of medical errors. An error in liver transplantation in August 2002 that cost the life of a baby led several researchers to recognize that there is still no national registry recording transplant mismatches. As a result, no one knows how many cases occur each year, let alone find ways to improve the present system.
  • Encourage patients to become more active participants in their own health care. This recommendation includes asking more questions and requesting adequate explanations from health-care professionals, as well as reporting medical errors.
  • Address the fact that both patients and physicians have emotional as well as knowledge-related needs around the issue of medical errors. A report published in the Journal of the American Medical Association in February 2003 stated that patients clearly want emotional support from their doctors following an error, including an apology. The researchers also found, however, that doctors are as upset when an error occurs and, additionally, are unsure where to turn for emotional support.
  • Adopt a teamwork rather than an individualistic approach to medical care. According to an article published in 2005 in the Annals of Internal Medicine, health care teams make fewer mistakes than individuals.

What patients can do

Patients are an important resource in lowering the rate of medical errors. The QuIC task force has put together some fact sheets to help patients improve the safety of their health care. One of these fact sheets, entitled “Five Steps to Safer Health Care,” gives the following tips:

  • Do not hesitate to ask questions of your health-care provider, and ask him or her for explanations that you can understand.
  • Keep lists of all medications, including over-the-counter items as well as prescribed drugs.
  • Ask for the results of all tests and procedures, and find out what the results mean for you.
  • Find out what choices are available to you if your doctor recommends hospital care.
  • If your doctor suggests surgery, ask for information about the procedure itself, the reasons for it, and exactly what will happen during the operation.

This fact sheet, as well as a longer and more detailed patient fact sheet on medical errors, is available for free download from the Agency for Health Research and Quality (AHRQ) Website, or by telephone order from the AHRQ Publications Clearinghouse at (800) 358-9295. In addition, the AHRQ has set up a patient safety network website at <> The website has an extensive list of resources ranging from online articles and fact sheets to links to audiovisual materials, journal articles, government reports, and other online materials. The site is produced and maintained by a team of editors at the University of California, San Francisco.



Committee on Quality of Health Care in America, Institute of Medicine. To Err Is Human: Building a Safer Health System. Washington, DC: National Academy Press, 2000.

Dhillon, B. S. Reliability Technology, Human Error, and Quality in Health Care. Boca Raton, FL: Taylor and Francis, 2007.

Peters, George A., and Barbara J. Peters. Medical Error and Patient Safety: Human Factors in Medicine. Boca Raton, FL: CRC Press/Taylor and Francis, 2008.

Woods, Michael S. Healing Words: The Power of Apology in Medicine, 2nd ed. Oakbrook Terrace, IL: Joint Commission Resources, 2007.


Aiken, Linda H., et al. “Hospital Nurse Staffing and Patient Mortality, Nurse Burnout, and Job Dissatisfaction.” Journal of the American Medical Association 288 (October 23-30, 2002): 1987–1993.

Amalberti, Rene, Yves Auroy, Don Berwick, and Paul Bar-ach. “Five System Barriers to Achieving Ultrasafe Health Care.” Annals of Internal Medicine 142 (May 3, 2005): 756–764.

Cottrill, Ken. “Mistaken Identity: Barcoding Recommended to Combat Medical Errors.” Traffic World (July 2, 2001).

Farley, Peter. “Redesigning the Residency.” Yale Medicine 39 (Fall/Winter 2004): 22–24.

Friedman, Richard A. “Do Spelling and Penmanship Count? In Medicine, You Bet.” New York Times March 11, 2003.

Gallagher, T. H., et al. “Patients’ and Physicians’ Attitudes Regarding the Disclosure of Medical Errors.” Journal of the American Medical Association 289 (February 26, 2003): 1001–1007.

Gawande, Atul. “Annals of Medicine: The Checklist.” New Yorker, December 10, 2007. Available online at [cited January 7, 2008].

Grady, Denise, and Lawrence K. Altman. “Suit Says Transplant Error Was Cause in Baby’s Death in August.” New York Times March 12, 2003.

Hsia, David C. “Medicare Quality Improvement: Bad Apples or Bad Systems?” Journal of the American Medical Association 289 (January 15, 2003): 354–356.

Leonhardt, David. “Why Doctors So Often Get It Wrong.” New York Times, February 22, 2006. Available online at [cited January 7, 2008].

Lockley, S. W., L. K. Barger, N. T. Ayas, et al. “Effects of Health Care Provider Work Hours and Sleep Deprivation on Safety and Performance.” Joint Commission Journal on Quality and Patient Safety 33 (November 2007): 7–18.

Olden, P. C., and W. C. McCaughrin. “Designing Health-care Organizations to Reduce Medical Errors and Enhance Patient Safety.” Hospital Topics 85 (Fall 2007): 4–9.

Pyzdek, Thomas. “Motorola’s Six Sigma Program.” Quality Digest (December, 1997).


Agency for Healthcare Research and Quality (AHRQ). 540 Gaither Road, Rockville, MD 20850. (301) 427-1364. <>.

Institute of Medicine (IOM). The National Academies. 500 Fifth Street, NW, Washington, DC 20001.

National Patient Safety Foundation (NPSF). 132 MASS MoCA Way, North Adams, MA 01247. (413) 663-8900. <>.

United States Food and Drug Administration (FDA). 5600 Fishers Lane, Rockville, MD 20857-0001. (888) 463-6332.


Agency for Healthcare Research and Quality (AHRQ) Fact Sheet. Medical Errors: The Scope of the Problem. Publication No. AHRQ 00-PO37.

Agency for Healthcare Research and Quality (AHRQ) Patient Fact Sheet. 20 Tips to Help Prevent Medical Errors. Publication No. AHRQ 00-PO38.

Burton, Susan. “The Biggest Mistake of Their Lives.” New York Times, March 16, 2003.

Quality Interagency Coordination Task Force (QuIC) Patient Fact Sheet. Five Steps to Safer Health Care, January 2001 [cited March 17, 2003].

Report of the Quality Interagency Coordination Task Force (QuIC) to the President. Doing What Counts for Patient Safety: Federal Actions to Reduce Medical Errors and Their Impact, 2000.

Rebecca Frey, PhD

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Medical Errors

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