Defining medical error

Abstract

Medical errors represent a serious public health problem and pose a threat to patient safety. As health care institutions establish "error" as a clinical and research priority, the answer to perhaps the most fundamental question remains elusive: What is a medical error? To reduce medical error, accurate measurements of its incidence, based on clear and consistent definitions, are essential prerequisites for effective action. Despite a growing body of literature and research on error in medicine, few studies have defined or measured "medical error" directly. Instead, researchers have adopted surrogate measures of error that largely depend on adverse patient outcomes or injury (i.e., are outcome-dependent). A lack of standardized nomenclature and the use of multiple and overlapping definitions of medical error have hindered data synthesis, analysis, collaborative work and evaluation of the impact of changes in health care delivery. The primary objective of this review is to highlight the need for a clear, comprehensive and universally accepted definition of medical error that explicitly includes the key domains of error causation and captures the faulty processes that cause errors, irrespective of outcome.

FIG. 1. James Reason's “Swiss cheese” model of error causation. In complex organizations (hospitals, clinics, biomedical institutes), medical errors cause adverse patient outcomes only when they penetrate through the holes or flaws in the multiple layers of defence (slices of Swiss cheese).