What is an error?
BACKGROUND
Launched by the Institute of Medicine's report, "To Err is Human," the reduction of medical errors has become a top agenda item for virtually every part of the U.S. health care system.


OBJECTIVE
To identify existing definitions of error, to determine the major issues in measuring errors, and to present recommendations for how best to proceed.


METHODS
Medical literature on errors as well as the sociology and industrial psychology literature cited therein.


RESULTS
We have four principal observations. First, errors have been defined in terms of failed processes without any link to subsequent harm. Second, only a few studies have actually measured errors, and these have not described the reliability of the measurement. Third, no studies directly examine the relationship between errors and adverse events. Fourth, the value of pursuing latent system errors (a concept pertaining to small, often trivial structure and process problems that interact in complex ways to produce catastrophe) using case studies or root cause analysis has not been demonstrated in either the medical or nonmedical literature.


CONCLUSIONS
Medical error should be defined in terms of failed processes that are clearly linked to adverse outcomes. Efforts to reduce errors should be proportional to their impact on outcomes (preventable morbidity, mortality, and patient satisfaction) and the cost of preventing them. The error and the quality movements are analogous and require the same rigorous epidemiologic approach to establish which relationships are causal.
Hofer
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Department of Veterans Affairs, VA Center for Practice Management and Outcomes Research, VA Ann Arbor Healthcare System, Ann Arbor, Mich., USA. thofer@umich.edu
Kerr
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Hayward
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D015984:Causality; D004812:Epidemiologic Methods; D006801:Humans; D007049:Iatrogenic Disease / Q000517:prevention & control; D008318:Malpractice; D019300:Medical Errors / Q000145:classification* / Q000517:prevention & control; D015969:National Academies of Science, Engineering, and Medicine, U.S., Health and Medicine Division; D010043:Outcome and Process Assessment, Health Care / Q000379:methods*; D011785:Quality Assurance, Health Care; D012308:Risk Management / Q000379:methods*; D014481:United States