ToxicologyAdverse drug events in emergency department patients*,**
Introduction
The publication of the Institute of Medicine report on medical errors exposed preventable adverse drug events (ADEs) as an important and previously underrecognized cause of medical injury.1 An ADE is an injury (noxious or harmful effect) resulting from medical intervention related to a drug.2 Studies of the incidence, severity, and cost of ADEs in hospitalized patients have found that between 2.4% and 6.5% of hospitalized patients have an ADE (>770,000 US hospital patients annually), with direct costs between US$1.56 and $4.2 billion annually and an estimated total cost of $12.2 billion in 1996 dollars.2, 3, 4, 5
Although much ADE research thus far has focused on hospital inpatient populations, less is known about emergency department ADEs. Previous reports have noted that ED patients are at high risk for adverse drug interactions (ADIs) and that drug-related illness is not uncommon in the ED.6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 However, the full scope of ADE-related ED visits and the factors that put patients at risk for ADEs remain largely unknown. Inpatient ADEs are most common in the ICU, perhaps because these patients are sicker and require more medications.2, 4, 18, 2018-20 EDs also evaluate many patients with high-severity illnesses who take multiple medications, and we hypothesize that ADEs are also common in this population.
The objective of this study was to measure the incidence of ADEs in an ED population, classify the severity and disposition of ADE visits, quantitate the costs of ADEs in the ED, and identify risk factors for ADEs within an ED population.
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Materials and methods
With more than 59,000 annual ED visits and 731 inpatients beds, the study site ED and medical center is the primary teaching hospital for a university medical school and serves as both a primary and tertiary referral center for a surrounding urban and rural population of greater than 2 million persons. Board-certified attending emergency physicians, emergency resident physicians, and rotating off-service resident physicians collaboratively care for a mixed payor population in the ED.
All
Results
During the study period, 13,602 ED visits occurred, with 13,004 (95.6%) ED charts available for review and 321 (2.5% of reviewed ED charts) suspected ADE visits identified. Evaluation of the suspected ADE visit group yielded 217 (1.7% of total reviewed ED charts) visits with a Naranjo ADR probability scale score of greater than 4; these visits were classified as probable ADEs and were compared with control visits. Investigators were highly concordant in assigning Naranjo ADR probability scale
Discussion
ADEs comprise an important proportion of ED visits, ranking higher than common ED diagnoses, such as syncope, pneumonia, and pharyngitis. ADEs usually occurred before ED evaluation, and most patients presented primarily for ADE symptomatology. Few identified ADEs were fatal or life threatening, but most were considered significant. Compared with a control population, patients with ADEs were older, took more medications, and were more frequently hospitalized. ADE visits resulted in a diagnosis
Acknowledgements
Author contributions: SMB and MDS conceived the study and SMB, MDS, and JWH developed its design. JWH and KAB acquired the data. SMB and JWH managed the data, and SMB oversaw quality control. SMB, JWH, and MDS analyzed and interpreted the data and SMB provided statistical advice. JWH drafted the manuscript, and SMB and MDS contributed substantially to its revision. JWH and SMB take responsibility for the paper as a whole.
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Author contributions are provided at the end of this article.
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Address for reprints: John W. Hafner, Jr., MD, Department of Emergency Medicine, OSF Saint Francis Medical Center, 530 NE, Glen Oak Avenue, Peoria, IL 61637; 309-655-2553, fax 309-655-2602; [email protected];[email protected].