Patient safety/original research
Do Emergency Physicians Attribute Drug-Related Emergency Department Visits to Medication-Related Problems?

https://doi.org/10.1016/j.annemergmed.2009.10.008Get rights and content

Study objective

Adverse drug events represent the most common cause of preventable nonsurgical adverse events in medicine but may remain undetected. Our objective is to determine the proportion of drug-related visits emergency physicians attribute to medication-related problems.

Methods

This prospective observational study enrolled adults presenting to a tertiary care emergency department (ED) during 12 weeks. Drug-related visits were defined as ED visits caused by adverse drug events. The definition of adverse drug event was varied to examine both narrow and broad adverse drug event classification systems. Clinical pharmacists evaluated all patients for drug-related visits, using standardized assessment algorithms, and then followed patients until hospital discharge. Interrater agreement for the clinical pharmacist diagnosis of drug-related visit was assessed. Emergency physicians, blinded to the clinical pharmacist opinion, were interviewed at the end of each shift to determine whether they attributed the visit to a medication-related problem. An independent committee reviewed and adjudicated all cases in which the emergency physicians' and clinical pharmacists' assessments were discordant, or either the emergency physician or clinical pharmacist was uncertain. The primary outcome was the proportion of drug-related visits attributed to a medication-related problem by emergency physicians.

Results

Nine hundred forty-four patients were enrolled, of whom 44 patients received a diagnosis of the narrowest definition of an adverse drug event, an adverse drug reaction (4.7%; 95% confidence interval [CI] 3.5% to 6.2%). Twenty-seven of these were categorized as medication-related by emergency physicians (61.4%; 95% CI 46.5% to 74.3%), 10 were categorized as uncertain (22.7%; 95% CI 12.9% to 37.1%), and 7 categorized as a non-medication-related problem (15.9%; 95% CI 8.0% to 29.5%). Seventy-eight patients (8.3%; 95% CI 6.7% to 10.2%) received a diagnosis of an adverse drug event caused by an adverse drug reaction, a drug interaction, drug withdrawal, a medication error, or noncompliance. Emergency physicians attributed 49 of these to a medication-related problem (62.8%; 95% CI 51.7% to 72.7%), were uncertain about 15 (19.2%; 95% CI 12.0% to 29.4%), and attributed 14 to non-medication-related problems (17.9%; 95% CI 11.0% to 27.9%). Twenty-five of 29 (86.2%; 95% CI 69.3% to 94.4%) adverse drug events not considered medication related by emergency physicians were rated at least moderate in severity.

Conclusion

A significant proportion of drug-related visits are not deemed medication related by emergency physicians. Drug-related visits not attributed to medication-related problems by emergency physicians may be missed in ongoing outpatient adverse drug event surveillance programs intended to develop strategies to enhance drug safety. Further research is needed to determine what the effect may be of not attributing adverse drug events to medication-related problems.

Introduction

In 2000, the Institute of Medicine estimated that adverse events due to medical care were responsible for 100,000 deaths in the United States annually, a greater number than occurred from motor vehicle crashes, AIDS, and breast cancer combined.1, 2, 3, 4 Adverse drug events are untoward and unintended events arising from the use or misuse of medications5 and represent the most common cause of preventable nonsurgical adverse events in medicine. Adverse drug events are therefore prime targets for patient safety initiatives.6, 7, 8, 9

Outpatient adverse drug events pose a significant burden to the health care system. Prospective research indicates that adverse drug events cause up to 12% of adult tertiary care emergency department (ED) visits.10, 11, 12, 13, 14, 15 Understanding emergency physicians' attribution of adverse drug events to medication-related problems is important to ensure that medication regimens are optimized and that patients and their care providers receive feedback, education, and interventions that could help reduce recurrences.16, 17 In addition, understanding emergency physicians' ability to attribute adverse drug events to medication-related problems is necessary to appreciate the limitations of ongoing ED-based outpatient drug safety surveillance programs such as the National Electronic Injury Surveillance System–Cooperative Adverse Drug Event Surveillance project (NEISS-CADES),18, 19, 20, 21 the goal of which is to generate national ED data on outpatient adverse drug events to enhance postmarketing surveillance of new drugs and enable the development of preventive strategies. NEISS-CADES and other surveillance initiatives are based on retrospective medical record review by trained coders and thereby rely on emergency physician identification and documentation of adverse drug events for case finding.

To our knowledge, the only published study to date examining emergency physician identification of adverse drug events was conducted on a small sample of high-risk elderly.11 Emergency physicians attributed 91% of adverse drug events leading to ED presentation to medication use but only 32% of adverse drug events unrelated to the patients' chief complaint. Overall, emergency physicians attributed 49% of adverse drug events to medication-related problems, suggesting that half of adverse drug events remained undocumented when patients left the ED. However, the generalizability of this study's results were limited by nonsystematic and nonrepresentative patient enrollment and its restriction to geriatric patients for whom detection rates may have been inflated because of a high prevalence of drug-related problems.

In addition, the limited published data on emergency physician identification of adverse drug events does not address important limitations in current adverse drug event terminology: Historically, pharmacists and physicians have disagreed on adverse drug event definitions (Table 1). Pharmacists have adopted broader definitions than physicians, maintaining that narrow definitions miss readily treatable and preventable events occurring because of inappropriate prescribing, noncompliance, and sub- or supratherapeutic dosing, all of which pharmacists are trained to address, mitigate, and prevent, and for which effective pharmacist-led, ED-based interventions and other preventive recommendations could be developed.9, 16, 17, 22, 23 Because of this, emergency physicians' detection of a broad range of adverse drug events in the clinical setting is of interest.

The purpose of this study was to examine emergency physicians' identification of medication-related problems in patients presenting to the ED with adverse drug events. The primary objective was to determine the proportion of adverse drug events causing ED visits that emergency physicians attribute to medication-related problems. Secondary objectives were to describe unattributed adverse drug events, to examine related factors, and to examine whether adverse drug event attribution to medication-related problems varies with adverse drug event categorization.

Section snippets

Study Setting and Design

This was an a priori planned substudy of a large prospective observational study examining the incidence of adverse drug events leading to ED presentation.15 This study was conducted at Vancouver General Hospital, a 955-bed adult tertiary care referral and teaching hospital with an annual ED census of 72,000 patients in British Columbia, Canada. The ED is staffed by 26 emergency physicians certified in emergency medicine by the Royal College of Physicians and Surgeons of Canada. The University

Results

Of 1,194 patients who presented during data collection shifts and were selected for enrollment, 1,017 met the criteria for the primary study and 961 met inclusion criteria for this substudy (Figure). Emergency physician follow-up was successful in 944 cases (98.2%). Information was obtained by direct interview with the emergency physician at the end of the shift for 863 (91.4%) patients and by follow-up mail for 81 patients (8.6%). The baseline characteristics of the patient population are

Limitations

The purpose of this study was to examine emergency physician attribution of drug-related visits to medication-related problems. The decision to focus on adverse drug events causing the ED visit was made at the onset of the study and ensured that the adverse drug events studied were significant enough to result in a health care encounter. It is also consistent with ongoing national ED-based outpatient drug-safety surveillance efforts that are focused on identifying adverse drug events causing ED

Discussion

This is the first large study to prospectively examine emergency physicians' ability to attribute drug-related visits to medication-related problems. Our data suggest that emergency physicians attribute a smaller proportion of drug-related visits to medication-related problems than previously estimated.11

We believe that this study provides a more robust estimate of the true proportion of attributed events than previous research because of several methodological strengths. Our study used a

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    Provide feedback on this article at the journal's Web site, www.annemergmed.com.

    Supervising editor: Lewis S. Nelson, MD

    Author contributions: All authors conceived and designed the study, and all authors obtained funding. CMH and PJZ supervised the conduct of the study, data collection, and data management. CMH provided statistical expertise and analyzed the data. CMH drafted the article, and all authors contributed to its editing. All authors take responsibility for the paper as a whole.

    Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article that might create any potential conflict of interest. See the Manuscript Submission Agreement in this issue for examples of specific conflicts covered by this statement. This work was supported by a grant from the Vancouver Coastal Health Research Institute In It for Life fund. Dr. Hohl was supported by a Mentored Clinician Scientist award from the Vancouver Coastal Health Research Institute. Dr. Abu-Laban was supported by a Clinical Scholar Award from the Michael Smith Foundation for Health Research.

    Publication date: Available online December 11, 2009.

    Reprints not available from the authors.

    Please see page 494 for the Editor's Capsule Summary of this article.

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