The possibility of a medical error worries many people in today's complex health care system. When health care or services have an unexpected and undesired result, it is called an adverse event. An adverse event may be caused by a medical error when something that was planned as a part of medical care doesn't work out or when the wrong plan was used in the first place. Medical errors can occur anywhere in the health care system: in hospitals, clinics, outpatient surgery centers, health professionals' offices, nursing homes, pharmacies, and patients' homes. Errors can involve medicines, surgery, diagnosis, equipment, or lab reports. They can occur during even the most routine tasks, such as when a hospital patient on a salt-free diet is given the wrong meal.

Most errors result from problems created by today's complex health care system. Errors also occur when health professionals and their patients have problems communicating. For example, one study supported by the U.S. Agency for Healthcare Research and Quality (AHRQ) found that health professionals sometimes do not help their patients make informed decisions. Uninvolved and uninformed patients are less likely to accept their health professional's recommended treatment and less likely to do what they need to do to make the treatment work.¹

Medical errors are one of the nation's leading causes of death and injury. A report by the Institute of Medicine estimates that as many as 44,000 to 98,000 people die in American hospitals each year as the result of medical errors. This means that more people die from medical errors than from motor vehicle accidents, breast cancer, or AIDS.¹

Government agencies, purchasers of group health care, and health professionals are working together to make the United States health care system safer.

There are many things you can do to work in partnership with your health professional to prevent medical errors.