Original Research

Classification of medical errors and preventable adverse events in primary care: A synthesis of the literature

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OBJECTIVE: To describe and classify process errors and preventable adverse events that occur from medical care in outpatient primary care settings.

STUDY DESIGN: Systematic review and synthesis of the medical literature.

DATA SOURCES: We searched MEDLINE and the Cochrane Library from 1965 through March 2001 with the MESH term medical errors, modified by adding family practice, primary health care, physicians/family, or ambulatory care and limited the search to English-language publications. Published bibliographies and Web sites from patient safety and primary care organizations were also reviewed for unpublished reports, presentations, and leads to other sites, journals, or investigators with relevant work. Additional papers were identified from the references of the papers reviewed and from seminal papers in the field.

OUTCOMES MEASURED: Process errors and preventable adverse events.

RESULTS: Four original research studies directly studied and described medical errors and adverse events in primary care, and 3 other studies peripherally addressed primary care medical errors. A variety of quantitative and qualitative methods were used in the studies. Extraction of results from the studies led to a classification of 3 main categories of preventable adverse events: diagnosis, treatment, and preventive services. Process errors were classified into 4 categories: clinician, communication, administration, and blunt end.

CONCLUSIONS: Original research on medical errors in the primary care setting consists of a limited number of small studies that offer a rich description of medical errors and preventable adverse events primarily from the physician’s viewpoint. We describe a classification derived from these studies that is based on the actual practice of primary care and provides a starting point for future epidemiologic and interventional research. Missing are studies that have patient, consumer, or other health care provider input.


  • Little is known about medical errors and preventable adverse events in the primary care setting.
  • Preventable adverse events reported from primary care practices include diagnostic, treatment, and preventive care incidents.
  • Process errors reported from primary care practices can be categorized as clinician factors (judgment, decision making, skill execution), communication factors (between clinician and patient and between health care providers), administration factors (office and personnel issues), and blunt end factors (insurance and government regulations).
  • Current knowledge of errors and preventable adverse events in primary care is missing input from patients and other health care providers.

Every primary care clinician in the United States knows the frustration of lost charts, misplaced reports, and messages from patients that should have been answered yesterday. These are some of the common frustrations and failures in day-to-day clinical practice. Many clinicians also know the guilt, shame, and self-doubt that occur when patients suffer a serious complication or die due to a mistake made by the clinician, health care team, or health care system. Between the common frustrations of practice and the rare patient death due to an error lies a large chasm, a rarely explored territory of relationships, causes and effects, and mitigating factors. Looking backward from a catastrophic patient outcome rarely goes beyond blaming the immediate person “at fault.” 1 Looking forward from common charting errors rarely goes beyond a conclusion to be “more careful.”

Hospital-based research has categorized preventable adverse outcomes and some process errors associated with them,2-4 but this has not been done in primary care.5 There are difficulties in studying errors in the primary care setting: care takes place in many locations; involves multiple visits; is provided in person, by phone, by mail, and even by computer; and involves interactions with many health care workers. However, it is important to study errors in primary care6 because it is the location of most health care visits in the United States.7

A classification or taxonomy of errors and preventable adverse events is an important first step in improving patient care. Prevalence and epidemiology studies, clinical and system interventions, and even individual practice group databases of errors and adverse events8 can more easily be developed if there is a beginning classification system. Just as clinicians use a differential diagnostic list for analyzing symptoms or a list of risk factors for assessing disease, so, too, can clinicians use a classification and listing of process errors and preventable adverse events to “diagnose” and “prevent” patient harm from medical care. Many taxonomies of medical error do exist and have been used in hospital accreditation or malpractice contexts for some time.9 These taxonomies have not been generally available for purposes other than their intended use, ie, to help their developers understand the data they were dealing with, and because these data do not originate from primary care practice, it remains unknown how well the taxonomies might meet the needs of family physicians and other primary care researchers.


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