Adverse event: An untoward and usually unanticipated outcome that occurs in association with health care.
Harm: Death or impairment of a body function or structure requiring intervention.
Hazard: A setting or technology that has the potential to cause harm.
Health care associated injury: Harm caused to the patient through medical error and not as a result of the natural course of a patient's condition.
Health care environment: The structures and processes employed to provide care. Reflects the characteristics of the facility (e.g., size, location, specialty, licensure, certification, equipment); and the organization (e.g., personnel mix and experience, lines of authority, policies and procedures, governance, leadership, culture).
Medical errors: Mistakes made in the process of care that result in or have the potential to result in harm to patients. Mistakes include the failure of a planned action to be completed as intended or the use of a wrong plan to achieve an aim. Can be the result of an action that is taken (error of commission) or an action that is not taken (error of omission).
Medication Error: Preventable inappropriate use of medication including prescribing, dispensing, and administering.
Patient safety: The absence of the potential for or occurrence of health care associated injury to patients. Created by avoiding medical errors as well as taking action to prevent errors from causing injury.
Preventable injury: Harm that could be avoided through reasonable planning or proper execution of an action.
* We attempted to define these terms using nontechnical language. Definitions related to patient safety are the source of some controversy and disagreement among stakeholders. While the terms in this report have been used according to the definitions above, the definitions are likely to evolve over time as researchers, practitioners, policymakers, patients, and others gain experience with the terms and consensus develops around usage.