Errors in Health Care: A Leading Cause of Death and Injury

Introduction

Although the literature pertaining to errors in health care has grown steadily over the last decade and some notable studies are particularly strong methodologically, we do not yet have a complete picture of the epidemiology of errors. Many studies focus on patients experiencing injury and provide valuable insight into the magnitude of harm resulting from errors. Other studies, more limited in number, focus on the occurrence of errors, both those that result in harm and those that do not (sometimes called ”near misses”). More is known about errors that occur in hospitals than in other health care delivery settings.

Synthesizing and interpreting the findings in the literature pertaining to errors in health care is complicated due to the absence of standardized nomenclature. For purposes of this report, the terms error and adverse event are defined as follows:

An error is defined as the failure of a planned action to be completed as intended (i.e., error of execution) or the use of a wrong plan to achieve an aim (i.e., error of planning). ¹⁸

An adverse event is an injury caused by medical management rather than the underlying condition of the patient. An adverse event attributable to error is a “preventable adverse event.” ¹⁹ Negligent adverse events represent a subset of preventable adverse events that satisfy legal criteria used in determining negligence (i.e., whether the care provided failed to meet the standard of care reasonably expected of an average physician qualified to take care of the patient in question). ²⁰

When a study in the literature has used a definition that deviates from the above definitions, it is noted below.

Medication-related error has been studied extensively for several reasons: it is one of the most common types of error, substantial numbers of individuals are affected, and it accounts for a sizable increase in health care costs. ^{21 , 22 , 23} There are also methodologic issues: (1) prescription drugs are widely used, so it is easy to identify an adequate sample of patients who experience adverse drug events; (2) the drug prescribing process provides good documentation of medical decisions, and much of this documentation resides in automated, easily accessible databases; and (3) deaths attributable to medication errors are recorded on death certificates. There are probably other areas of health care delivery that have been studied to a lesser degree but may offer equal or greater opportunity for improvement in safety.

Efforts to assess the importance of various types of errors are currently hampered by the lack of a standardized taxonomy for reporting adverse events, errors, and risk factors. ^24 , 25 A limited number of studies focus directly on the causes of adverse events, but attempts to classify adverse events according to “root causes” are complicated by the fact that several interlocking factors often contribute to an error or series of errors that in turn result in an adverse event. ^26 , 27 In recent years, some progress toward a more standardized nomenclature and taxonomy has been made in the medication area, but much work remains to be done. ²⁸

The following discussion of the literature addresses four questions:

1.

How frequently do errors occur?

2.

What factors contribute to errors?

3.

What are the costs of errors?

4.

Are public perceptions of safety in health care consistent with the evidence?

How Frequently do Errors Occur?

For the most part, studies that provide insight into the incidence and prevalence of errors fall into two categories:

1.

General studies of patients experiencing adverse events. These are studies of adverse events in general, not studies limited to medication-related events. These studies are limited in number, but some represent large-scale, multi-institutional analyses. Virtually all studies in this category focus on hospitalized patients. With the exception of medication-related events discussed in the second category, little if any research has focused on errors or adverse events occurring outside of hospital settings, for example, in ambulatory care clinics, surgicenters, office practices, home health, or care administered by patients, their family, and friends at home.

2.

Studies of patients experiencing medication-related errors. There is an abundance of studies that fall into this category. Although many focus on errors and adverse events associated with ordering and administering medication to hospitalized patients, some studies focus on patients in ambulatory settings.