Neurology/original research
Variables Associated With Discordance Between Emergency Physician and Neurologist Diagnoses of Transient Ischemic Attacks in the Emergency Department

Presented as an abstract at the AHA 2010 International Stroke Conference, February 23-26, 2010, San Antonio, TX.
https://doi.org/10.1016/j.annemergmed.2011.03.009Get rights and content

Study objective

Transient ischemic attack is a common clinical diagnosis in emergency department (ED) patients with acute neurologic complaints. Accurate diagnosis of transient ischemic attack is essential to help guide evaluation and avoid treatment delays. We seek to determine the prevalence of discordant diagnosis for patients receiving an ED diagnosis of transient ischemic attack compared with neurologist final diagnosis. Secondary goals are to evaluate the influence of atypical transient ischemic attack symptoms, the ABCD2 score, and emergency physician experience on discordant diagnoses.

Methods

We performed a retrospective cohort study evaluating all ED patients receiving a diagnosis of transient ischemic attack during a 4-year period. The emergency physician diagnosis was compared with that of the neurologist. The neurologist's final diagnosis was considered the criterion standard diagnosis. Subject demographic and clinical information was collected with a structured instrument. The following atypical symptoms present at the ED evaluation were evaluated with logistic regression: headache, tingling, involuntary movement, seeing flashing lights or wavy lines, dizziness, confusion, incontinence, and ABCD2 score of 4 or greater. Bivariate analysis was used to evaluate the influence of emergency physician experience (≤6 years versus >6 years) on discordant diagnosis. Odds ratios (ORs) and proportions are reported with 95% confidence intervals (CIs), interquartile range was used where appropriate.

Results

We evaluated 436 subjects, of whom 7 were excluded, allowing 429 subjects for evaluation. Of these individuals, 156 (36%; 95% CI 32% to 41%) received a discordant diagnosis. The median emergency physician time in clinical practice was 6 years (interquartile range 2 to 12 years). Features associated with a discordant transient ischemic attack diagnosis included headache (OR 2.52; 95% CI 1.59 to 3.99), involuntary movement (OR 3.19; 95% CI 1.35 to 7.54), and dizziness (OR 1.92; 95% CI 1.22 to 3.02). Incontinence, confusion, and seeing wavy lines or flashing lights were not significantly associated with a discordant diagnosis. Patients with tingling and a high ABCD2 score had an increased odds of concordant transient ischemic attack diagnosis (OR 0.54, 95% CI 0.32 to 0.92; OR 0.53, 95% CI 0.35 to 0.82, respectively).

Conclusion

Discordant diagnoses between emergency physicians and neurologists were observed in 36% of patients. The presence of headache, involuntary movement, and dizziness predicted discordant diagnoses, whereas the presence of tingling and an increased ABCD2 score predicted concordant transient ischemic attack diagnosis.

Introduction

Cerebral transient ischemic attacks have been known to be a precursor for ischemic strokes for more than a century; however, the true risk of stroke shortly after transient ischemic attack has been well defined only in the last decade.1, 2, 3, 4 The risk of stroke after transient ischemic attack is 5% in the first 48 hours and ranges from 10% to 15% in the next 90 days, whereas the risk of other adverse cardiovascular events in the same period is 25%.1, 3 Previously, transient ischemic attack management was considered nonemergency and often managed in the outpatient setting. Recent guidelines for the management of transient ischemic attack have recommended hospitalization for severe transient ischemic attack or urgent referral and testing for recent transient ischemic attack.5, 6

The definition of transient ischemic attack has been controversial.7 A recent scientific statement from the American Heart Association has recommended the definition of transient ischemic attack to be a “brief episode of neurologic dysfunction caused by focal brain or retinal ischemia, with clinical symptoms typically lasting less than one hour, and without evidence of acute infarction.”6, 8 This definition eliminates the previous 24-hour time limit used to distinguish a transient ischemic attack from cerebral infarction. It also reclassifies patients with evidence of clinically silent acute cerebral infarction from transient ischemic attack to stroke. These changes have come in part from advances in neuroimaging that have shown that one third of transient ischemic attack patients have evidence of cerebral infarction on diffusion-weighted magnetic resonance imaging (MRI).6 Despite these changes, the diagnosis of transient ischemic attack still relies on an accurate interpretation of clinical history and physical examination leading to suspected focal brain ischemia.

Certain clinical features have been suggested to be atypical of transient ischemic attack, such as headache, incontinence, dizziness, and confusion.8 With the exception of dizziness, to our knowledge none of these atypical features have been evaluated to determine their association with a final diagnosis of transient ischemic attack. More recent tools have been used to assist with the accurate diagnosis of transient ischemic attack. The ABCD2 rule was developed as a risk-stratification tool for transient ischemic attack patients and the risk of subsequent short-term stroke.9 This rule has been assessed to determine whether higher ABCD2 scores predict true transient ischemic attacks. Two studies have shown that patients with higher scores at transient ischemic attack evaluation have a higher likelihood of correct transient ischemic attack or minor ischemic stroke diagnosis.10, 11

Appropriate ED diagnosis of transient ischemic attack is important because patients presenting with transient ischemic attack will often be admitted and undergo evaluations including computed tomography (CT), echocardiography, and carotid evaluation by means of ultrasonography or CT angiography and MRI/magnetic resonance angiography.12 These tests carry risks of radiation exposure and intravenous dye exposure and represent a significant medical expense. If prevalence of misdiagnosis were occurring at high rates, this would represent a major public health problem because transient ischemic attack is diagnosed in emergency departments (EDs) almost 300,000 times a year.13

The prevalence of correct transient ischemic attack diagnosis by emergency physicians is variable, according to previously published research. A recent study evaluating ED misdiagnosis of transient ischemic attack concluded the emergency physician prevalence of misdiagnosis of transient ischemic attack was 60%.14 Other studies have suggested that the prevalence of misdiagnosis is much lower, approaching 10% or less.10, 15 The ability of emergency physicians to accurately diagnose transient ischemic attack is important because rapid evaluation and treatment have been shown to decrease the rate of cerebral infarction.16, 17, 18 Once an incorrect diagnosis is made, inappropriate testing may occur, and it is uncertain when the inaccurate diagnosis will be corrected.

Practice patterns for neurologists' treatment of transient ischemic attack patients are unclear. Patients may be admitted and undergo testing only to be referred to a neurologist as outpatients. Also it is becoming increasingly common for transient ischemic attack patients to be admitted to observation units, where their evaluation will be completed by emergency physicians or hospitalists. These units are often protocol driven: testing may be ordered automatically. It may be the day after testing is complete before a neurologist decides that the patient had a non–transient ischemic attack event.

Our primary goal was to determine the prevalence of discordant diagnosis for patients receiving an ED diagnosis of transient ischemic attack compared with a neurologist's final diagnosis. Our secondary goals were to determine the frequency of atypical symptoms and what association these symptoms and the ABCD2 score had on a discordant ED transient ischemic attack diagnosis and to determine whether emergency physician experience was related to the risk of an ED transient ischemic attack discordant diagnosis.

Section snippets

Study Design

We conducted a planned secondary analysis of a previous retrospective cohort study evaluating all patients receiving an ED diagnosis of transient ischemic attack from January 2004 through December 2007. The primary study was an evaluation of the ability of the ABCD2 score, a transient ischemic attack prognostic tool, to predict positive results of diagnostic testing performed on transient ischemic attack patients.12 Our hospital is a county-owned ED with an annual census of more than 90,000

Results

We reviewed 436 subjects who received a diagnosis of transient ischemic attack in the ED, of whom 7 met exclusion criteria, allowing 429 subjects for final analysis. The demographics for the populations of discordant and concordant diagnoses can be seen in Table 1. These patients were evaluated by 47 unique emergency physicians with a median number of years of experience of 6 (interquartile range 2 to 12 years). The number of discordant transient ischemic attack diagnoses was 156 (36%; 95% CI

Limitations

This study has several limitations. It was conducted at a single center, so our results may not be applicable in other locations. The criterion standard of neurologist diagnosis of transient ischemic attack is problematic. Because there is no clinical diagnostic test that definitively diagnoses transient ischemic attack, we were limited to this criterion standard. The use of diffusion-weighted MRI was not considered as a surrogate criterion standard because a limited number of patients would

Discussion

Transient ischemic attack is a common disease that can present with a wide variability of clinical symptoms. The symptoms may be subtle, such as slight numbness or weakness, or as dramatic as hemiplegia or aphasia. The diagnosis of transient ischemic attack in the ED is a clinical diagnosis without the benefit of biomarkers or other diagnostic tests that may be of assistance. At this time, there is no current diagnostic test considered to be definitive for the diagnosis of transient ischemic

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    Supervising editor: Allan B. Wolfson, MD

    Author contributions: JWS, AV, and RKC were responsible for study design. JWS, MG, AV, and TL were responsible for data collection. JWS and RKC were responsible for statistical analysis and article preparation. JWS takes 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 as per ICMJE conflict of interest guidelines (see www.icmje.org). The authors have stated that no such relationships exist. Funding for Mr. Victor was provided by the Edward M. Chester, MD, Summer Scholars Program.

    Publication date: Available online May 31, 2011.

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