Ilana Spokoyny, MD
Arch AE, Weisman DC, Coca S, Nystrom KV, Wira III CR, Schindler JL. Missed Ischemic Stroke Diagnosis in the Emergency Department by Emergency Medicine and Neurology Services. Stroke. 2016

Ischemic stroke presentations can vary significantly and some presentations are more likely to be overlooked or thought to be stroke mimics. Additionally, some patient populations (such as young patients, women, and minorities) are more likely to be attributed nonstroke etiologies. The danger is, of course, missed treatment opportunities. However, patients with missed strokes are also less likely to receive appropriate monitoring for neurological progression or stroke-related complications.

The authors of this study performed a retrospective chart review to determine the rates of diagnosis and misdiagnosis of stroke patients at one academic hospital and one community hospital. Patients were identified by discharge billing code. TIAs were excluded, as were imaging-negative strokes. A stroke was “missed” if practitioners in the Emergency Department (ED) did not initially consider stroke in the differential or the diagnosis was delayed, causing the patient to miss the therapeutic window for thrombolytic therapy. A stroke was also considered “missed” if ED physicians consulted neurology for a possible stroke diagnosis and the neurology consultant felt that the patient did not have a stroke and admitted the patient to a medicine service. 

A third of missed cases presented within a 3-hour time window, and an additional 11% presented within 3 to 6 hours. Of all missed cases of ischemic stroke at the academic hospital, 20/55 (35%) were seen by neurology in the ED but early diagnosis was still missed. Nine (45%) of these cases missed by neurology presented within the time window for rt-PA, and an additional 3 (15%) presented within 6 hours. Only 8% of missed stroke patients were triaged in the ED as stroke codes. Comparing these patients to those with accurate diagnoses, of whom 46% presented as stroke codes (p<0.001), the 46% seems low. However, stroke codes are not routinely called at this institution for patients who are out of the time window for intervention or clinical trial, and patients where acute cerebrovascular event is not part of the initial differential diagnosis. Forty percent of missed strokes patients did not have neurological examinations with elements of the NIHSS, compared with 8% of the accurately diagnosed stroke patients (p<0.001). Patients with nausea/vomiting, dizziness, and prior strokes were more likely to be misdiagnosed. Patients with focal weakness, vision changes, gaze preference, and dysarthria were more likely to be correctly diagnosed. More posterior strokes were initially misdiagnosed than anterior strokes. There did not appear to be a difference in the rates of misdiagnosis between an academic and community hospitals. For readmission rates, 33% of misdiagnosed patients were readmitted at 60 days post-discharge, compared with 17% of accurately diagnosed patients (p=0.012). 

The study population consisted of predominantly white, older adults who presented to an ED at a primary stroke center. A larger scale analysis would be important to perform, to determine if the rates of misdiagnosis vary among race/ethnicity. This study did not include truly misdiagnosed patients (those presenting with symptoms, who had a stroke that was never diagnosed, and who did not have brain imaging). It would be interesting to evaluate patients diagnosed with stroke who have had ED visits within the week prior to admission (for similar symptoms/presentation), to identify characteristics of truly misdiagnosed strokes. 

There are several factors identified in this study which can lead to systemic changes in the stroke triage process. First, there is a large discrepancy in the frequency of stroke codes called when comparing those with correct diagnoses to those who were missed. A balance must be found between high sensitivity and high specificity. Limiting the stroke code activation to those within the treatment window may be problematic. We know from other studies that the last known well time is often incorrectly identified in the ED, and that patients are only later refined into or out of the treatment window and their treatment options may change. Additionally, as the endovascular window extends, more patients may benefit from having acute neurologic evaluation in the ED, in the form of a stroke code. So, calling stroke codes on anyone with neurologic symptoms within a longer period of time, such as 12 hours, would greatly improve sensitivity. However, this comes at a resource costspecifically, neurology consultant time, CT scanner immediate availability, and pharmacy time spent at bedside. An analysis could be performed to determine how many additional stroke codes would have been activated with these broader criteria, and the resource cost of this, and compare this to how many additional patients would have been correctly identified and treated promptly. Overall, this was an eye-opening study on how we need to do better in the correct identification of our stroke patients.