Elsevier

The Lancet

Volume 349, Issue 9048, 1 February 1997, Pages 309-313
The Lancet

Articles
An alternative strategy for studying adverse events in medical care

https://doi.org/10.1016/S0140-6736(96)08268-2Get rights and content

Summary

Background

Data about the frequency of adverse events related to inappropriate care in hospitals come from studies of medical records as if they represented a true record of adverse events. In a prospective, observational design we analysed discussion of adverse events during the care of all patients admitted to three units of a large, urban teaching hospital affiliated to a university medical school. Discussion took place during routine clinical meetings. We undertook the study to enhance understanding of the incidence and scope of adverse events as a basis for preventing them.

Methods

Ethnographers trained in qualitative observational research attended day-shift, weekday, regularly scheduled attending rounds, residents' work rounds, nursing shift changes, case conferences, and other scheduled meetings in three study units as well as various departmental and section meetings. They recorded all adverse events during patient care discussed at these meetings and developed a classification scheme to code the data. Data were collected about health-care providers' own assessments about the appropriateness of the care that patients received to assess the nature and impact of adverse events and how health-care providers and patients responded to the adverse events.

Findings

Of the 1047 patients in the study, 185 (17·7%) were said to have had at least one serious adverse event; having an initial event was linked to the seriousness of the patient's underlying illness. Patients with long stays in hospital had more adverse events than those with short stays. The likelihood of experiencing an adverse event increased about 6% for each day of hospital stay. 37·8% of adverse events were caused by an individual, 15·6% had interactive causes, and 9·8% were due to administrative decisions. Although 17·7% of patients experienced serious events that led to longer hospital stays and increased costs to the patients, only 1·2% (13) of the 1047 patients made claims for compensation.

Interpretation

This study shows that there is a wide range of potential causes of adverse events that should be considered, and that careful attention must be paid to errors with interactive or administrative causes. Health-care providers' own discussions of adverse events can be a good source of data for proactive error prevention.

Introduction

Various terms are chosen to designate inappropriate care and adverse outcomes experienced by patients during their hospital care—adverse or untoward events, maloccurrences, complications, medical injuries, therapeutic misadventures, substandard care, unexpected outcomes, preventable deaths, iatrogenic injuries, mishaps, errors, negligence, or malpractice. This range of terms is complemented by an array of definitions chosen to suit the particular goals of the people using them. Within the hospital setting, the assessment of whether a health-care professional's action or inaction is appropriate or not may be undertaken for teaching purposes, for quality assurance purposes, for review of a provider's staff privileges, or to assess the provider's or hospital's potential legal liability. Outside researchers, using various methods, may enter the hospital environment with their own definitions of appropriate care to find out how the management of a particular type of diagnosis or treatment can be improved1, 2 or to assess the costs of implementing legal changes in the handling of malpractice cases, such as through the adoption of a no-fault system.3, 4, 5

In social-policy debates, the many potential definitions of appropriate care are ignored. Instead, data about the frequency of adverse events related to inappropriate care in hospitals come from studies of medical records as if they represented a “true” record of adverse events. For example, the Harvard Medical Practice Study of medical records is often regarded as an accurate indicator of the rate of adverse events in hospitals. That study found that 3·7% of 30 121 patient records from New York hospitals contained an incident that met the study's definition of an adverse event, which required consensus by two physicians and a specified level of harm.

This low incidence of adverse events contrasts substantially with prospective studies of certain types of care. For example, Brook's classic 1970 study1 found that only 27% of one cohort of patients seeking care in an emergency room received “effective medical care”. Steel and colleagues2 found that 36% of 815 consecutive patients had an iatrogenic illness, and 9% had an iatrogenic event that was life threatening or produced a disability. Meyers6 reported that “there is evidence, derived mainly from studies of hospital patients, that the denominator of iatrogenic illness and injury is large”.

To find out more about the care that patients receive than can be shown by prospective studies of particular procedures or after-the-fact analyses of medical records, we undertook a prospective, observational study of the care of all patients admitted to three units of a large urban teaching hospital. Our strategy was to assess how health-care professionals identified adverse events in the course of their normal tasks. We saw three benefits to such an approach. Since these meetings were designed for other purposes (such as teaching and patient care), adverse events needed to be discussed for the system to function. Thus, there was likely to be a fuller and more open account of such events than might occur in a survey of health-care providers about adverse events or even a study of medical records. Second, by monitoring all adverse events that were discussed about a patient's care, rather than studying how well a particular diagnosis or treatment was undertaken, we could begin to assess adverse events that might be due to institutional decisions and constraints, not merely technical or cognitive deficiencies on the part of the individual provider. Third, it seemed more likely that adverse events could be prevented if the health-care providers recognised that they were making them. Brennan notes that, in theory, all adverse events are preventable.7

Section snippets

Methods

The study was carried out in three units at a large, tertiary care, urban teaching hospital affiliated to a university medical school. The providers were the attending surgeons and physicians, fellows, residents, interns, nurses, and other health-care practitioners on ten surgical services. The study was approved by the hospital's Institutional Review Board. The techniques of data collection and analysis that were used protected the confidentiality of the sources and the patients.

Patients

During the study there were 1047 patients in the three units (mean age 46·5 years [SD 20·3], range 6 months-95 years); one-third of them were admitted more than once for a total of 1716 admissions. The patients were evenly distributed by sex and race, and their source of payment reflected the national distribution (table 1).

411 (39·3%) patients were in an intensive care unit at some point during the study. Median length of stay in the hospital (during all admissions that overlapped the research

Discussion

There is a growing published work of empirical investigations of the epidemiology of adverse events in the hospital setting. The most far-reaching research project studying adverse events to date has been the Harvard study of 30 121 New York hospital patients' records. The investigators defined adverse events according to a legal-policy model since their goal in measuring the event rate in hospitals was to determine the feasibility of a no-fault system of compensation for medical malpractice.

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