Compliance With Imaging Guidelines for Workup of Transient Ischemic Attack

Longitudinal changes in the US emergency department use of advanced neuroimaging in the mechanical thrombectomy era

PURPOSE

To describe ED neuroimaging trends across the time-period spanning the early adoption of endovascular therapy for acute stroke (2013-2018).

MATERIALS AND METHODS

We performed a retrospective, cross-sectional study of ED visits using the 2013-2018 National Emergency Department Sample, a 20% sample of ED encounters in the United States. Neuroimaging use was determined by Common Procedural Terminology (CPT) code for non-contrast head CT (NCCT), CT angiography head (CTA), CT perfusion (CTP), and MRI brain (MRI) in non-admitted ED patients. Data was analyzed according to sampling weights and imaging rates were calculated per 100,000 ED visits. Multivariate logistic regression analysis was performed to identify hospital-level factors associated with imaging utilization.

RESULTS

Study population comprised 571,935,906 weighted adult ED encounters. Image utilization increased between 2013 and 2018 for all modalities studied, although more pronounced in CTA (80.24/100,000 ED visits to 448.26/100,000 ED visits (p < 0.001)) and CTP (1.75/100,000 ED visits to 28.04/100,000 ED visits p < 0.001)). Regression analysis revealed that teaching hospitals were associated with higher odds of high CTA utilization (OR 1.88 for 2018, p < 0.05), while low-volume EDs and public hospitals showed the reverse (OR 0.39 in 2018, p < 0.05).

CONCLUSIONS

We identified substantial increases in overall neuroimaging use in a national sample of non-admitted emergency department encounters between 2013 and 2018 with variability in utilization according to both patient and hospital properties. Further investigation into the appropriateness of this imaging is required to ensure that access to acute stroke treatment is balanced against the timing and cost of over-imaging.

Factors Associated With Timeliness and Equity of Access to Outpatient MRI Examinations

OBJECTIVE

The role of MRI in guiding patients' diagnosis and treatment is increasing. Therefore, timely MRI performance prevents delays that can impact patient care. We assessed the timeliness of performing outpatient MRIs using the socio-ecological model approach and evaluated multilevel factors associated with delays.

METHODS

This institutional review board-approved study included outpatient MRI examinations ordered between October 1, 2021, and December 31, 2022, for performance at a large quaternary care health system. Mean order-to-performed (OtoP) interval (in days) and prolonged OtoP interval (defined as >10 days) for MRI orders with an expected date of 1 day to examination performance were measured. Logistic regression was used to assess patient-level (demographic and social determinants of health), radiology practice-level, and community-level factors associated with prolonged OtoP interval.

RESULTS

There were 126,079 MRI examination orders with expected performance within 1 day placed during the study period (56% of all MRI orders placed). After excluding duplicates, there were 97,160 orders for unique patients. Of the MRI orders, 48% had a prolonged OtoP interval, and mean OtoP interval was 18.5 days. Factors significantly associated with delay in MRI performance included public insurance (odds ratio [OR] = 1.11, P < .001), female gender (OR = 1.11, P < .001), radiology subspecialty (ie, cardiac, OR = 1.71, P < .001), and patients from areas that are most deprived (ie, highest Area Deprivation Index quintile, OR = 1.70, P < .001).

DISCUSSION

Nearly half of outpatient MRI orders were delayed, performed >10 days from the expected date selected by the ordering provider. Addressing multilevel factors associated with such delays may help enhance timeliness and equity of access to MRI examinations, potentially reducing diagnostic errors and treatment delays.

Association of Incomplete Neurovascular Imaging After Emergency Department Encounters for Transient Ischemic Attack and Odds of Subsequent Stroke: A National Medicare Analysis

BACKGROUND. Multisociety guidelines recommend urgent brain and neurovascular imaging for patients with transient ischemic attack (TIA), to identify and treat modifiable stroke risk factors. Prior research suggests that most patients with TIA who present to the emergency department (ED) do not receive prompt neurovascular imaging. OBJECTIVE. The purpose of this study was to evaluate the association between incomplete neurovascular imaging workup during ED encounters for TIA and the odds of subsequent stroke. METHODS. This retrospective study obtained data from the Medicare Standard Analytical Files for calendar years 2016 and 2017; these files contain 100% samples of claims for Medicare beneficiaries. Information was extracted using ICD 10th revision (ICD-10) and CPT codes. Those patients who were discharged from an ED encounter with a TIA diagnosis and who underwent brain CT or brain MRI during or within 2 days of the encounter were identified. Patients were considered to have complete neurovascular imaging if they underwent cross-sectional vascular imaging of both the brain (brain CTA or brain MRA) and neck (neck CTA, neck MRA, or carotid ultrasound) during or within 2 days of the encounter. The association between incomplete neurovascular imaging and a new stroke diagnosis within the subsequent 90 days was tested by multivariable logistic regression analysis. RESULTS. The sample included 111,417 patients (47,370 men, 64,047 women; 26.0% older than 84 years) who had TIA ED encounters. A total of 37.3% of patients (41,592) had an incomplete neurovascular imaging workup. A new stroke diagnosis within 90 days of the TIA ED encounter occurred in 4.4% (3040/69,825) of patients with complete neurovascular imaging versus 7.0% (2898/41,592) of patients with incomplete neurovascular imaging. Incomplete neurovascular imaging was associated with increased likelihood of stroke within 90 days (OR, 1.30 [95% CI, 1.23-1.38]) after adjustment for patient characteristics (age, sex, race and ethnicity, high-risk comorbidities, median county household income) and hospital characteristics (region, rurality, number of beds, major teaching hospital designation). CONCLUSION. TIA ED encounters with incomplete neurovascular imaging were associated with higher odds of subsequent stroke occurring within 90 days. CLINICAL IMPACT. Increased access to urgent neurovascular imaging for patients with TIA may represent a target that could facilitate detection and treatment of modifiable stroke risk factors.

When Can an Emergency CTA Be Dispensed with for TIA Patients?

Background: Transient ischemic attacks (TIAs) and minor strokes are often precursors of a major stroke. Therefore, diagnostic work-up of the TIA is essential to reduce the patient’s risk of further ischemic events. Purpose: With the help of this retrospective study, we aim to determine for which TIA patients a CT angiography (CTA) is not immediately necessary in order to reduce radiation exposure and nephrotoxicity. Material and Methods: Clinical and imaging data from patients who presented as an emergency case with a suspected diagnosis of TIA at a teaching hospital between January 2016 and December 2021 were evaluated. The included 1526 patients were divided into two groups—group 1, with major pathologic vascular findings in the CTA, and group 2, with minor vascular pathologies. Results: Out of 1821 patients with suspected TIA on admission, 1526 met the inclusion criteria. In total, 336 (22%) had major vascular pathologies on CTA, and 1190 (78%) were unremarkable. The majority of patients with major vascular pathologies were male and had a history of arterial hypertension, coronary heart disease, myocardial infarction, ischemic stroke, TIA, atherosclerotic peripheral vascular disease, smoking, antiplatelet medication, had a lower duration of TIA symptoms, and had lower ABCD2 scores. Conclusions: We were able to demonstrate a direct correlation between major CTA pathologies and a history of smoking, age, hyperlipidemia, history of peripheral arterial disease, and a history of stroke and TIA. We were able to prove that the ABCD2 score is even reciprocal to CTA pathology. This means that TIA patients without described risk factors do not immediately require a CTA and could be clarified in the course of treatment with ultrasound or MRI.

Lost to Follow-Up: A Nationwide Analysis of Patients With Transient Ischemic Attack Discharged From Emergency Departments With Incomplete Imaging

PURPOSE

Imaging guidelines for transient ischemic attack (TIA) recommend that patients undergo urgent brain and neurovascular imaging within 48 hours of symptom onset. Prior research suggests that most patients with TIA discharged from the emergency department (ED) do not complete recommended TIA imaging workup during their ED encounters. The purpose of this study was to determine the nationwide percentage of patients with TIA discharged from EDs with incomplete imaging workup who complete recommended imaging after discharge.

METHODS

Patients discharged from EDs with the diagnosis of TIA were identified from the Medicare 5% sample for 2017 and 2018 using International Classification of Diseases, tenth rev, Clinical Modification codes. Imaging performed was identified using Current Procedural Terminology codes. Incomplete imaging workup was defined as a TIA encounter without cross-sectional brain, brain-vascular, and neck-vascular imaging performed within the subsequent 30 days of the initial ED encounter. Patient- and hospital-level factors associated with incomplete TIA imaging were analyzed in a multivariable logistic regression.

RESULTS

In total, 6,346 consecutive TIA encounters were analyzed; 3,804 patients (59.9%) had complete TIA imaging workup during their ED encounters. Of the 2,542 patients discharged from EDs with incomplete imaging, 761 (29.9%) completed imaging during the subsequent 30 days after ED discharge. Among patients with TIA imaging workup completed after ED discharge, the median time to completion was 5 days. For patients discharged from EDs with incomplete imaging, the odds of incomplete TIA imaging at 30 days after discharge were highest for black (odds ratio, 1.84; 95% confidence interval, 1.27-2.66) and older (≥85 years of age; odds ratio, 2.41; 95% confidence interval, 1.78-3.26) patients. Reference values were age cohort 65 to 69 years; male gender; white race; no co-occurring diagnoses of hypertension, hyperlipidemia, or diabetes mellitus; household income > $63,029; hospital in the Northeast region; urban hospital location; hospital size > 400 beds; academically affiliated hospital; and facility with access to MRI.

CONCLUSIONS

Most patients discharged from EDs with incomplete TIA imaging workup do not complete recommended imaging within 30 days after discharge.

Nomograms predict prognosis and hospitalization time using non-contrast CT and CT perfusion in patients with ischemic stroke

Background

Stroke is a major disease with high morbidity and mortality worldwide. Currently, there is no quantitative method to evaluate the short-term prognosis and length of hospitalization of patients.

Purpose

We aimed to develop nomograms as prognosis predictors based on imaging characteristics from non-contrast computed tomography (NCCT) and CT perfusion (CTP) and clinical characteristics for predicting activity of daily living (ADL) and hospitalization time of patients with ischemic stroke.

Materials and methods

A total of 476 patients were enrolled in the study and divided into the training set (n = 381) and testing set (n = 95). Each of them owned NCCT and CTP images. We propose to extract imaging features representing as the Alberta stroke program early CT score (ASPECTS) values from NCCT, ischemic lesion volumes from CBF, and TMAX maps from CTP. Based on imaging features and clinical characteristics, we addressed two main issues: (1) predicting prognosis according to the Barthel index (BI)–binary logistic regression analysis was employed for feature selection, and the resulting nomogram was assessed in terms of discrimination capability, calibration, and clinical utility and (2) predicting the hospitalization time of patients–the Cox proportional hazard model was used for this purpose. After feature selection, another specific nomogram was established with calibration curves and time-dependent ROC curves for evaluation.

Results

In the task of predicting binary prognosis outcome, a nomogram was constructed with the area under the curve (AUC) value of 0.883 (95% CI: 0.781–0.985), the accuracy of 0.853, and F1-scores of 0.909 in the testing set. We further tried to predict discharge BI into four classes. Similar performance was achieved as an AUC of 0.890 in the testing set. In the task of predicting hospitalization time, the Cox proportional hazard model was used. The concordance index of the model was 0.700 (SE = 0.019), and AUCs for predicting discharge at a specific week were higher than 0.80, which demonstrated the superior performance of the model.

Conclusion

The novel non-invasive NCCT- and CTP-based nomograms could predict short-term ADL and hospitalization time of patients with ischemic stroke, thus allowing a personalized clinical outcome prediction and showing great potential in improving clinical efficiency.

Summary

Combining NCCT- and CTP-based nomograms could accurately predict short-term outcomes of patients with ischemic stroke, including whose discharge BI and the length of hospital stay.

Key Results

Using a large dataset of 1,310 patients, we show a novel nomogram with a good performance in predicting discharge BI class of patients (AUCs > 0.850). The second nomogram owns an excellent ability to predict the length of hospital stay (AUCs > 0.800).

Utilization of CT angiography of the head and neck in the era of endovascular therapy for acute ischemic stroke: a retrospective study

PURPOSE

To describe the impact of a new institutional Code Stroke protocol on ordering volume of head and neck CT angiographies (CTA), and to determine the number and proportion of these studies that resulted in an endovascular or surgical intervention.

METHODS

Clinical and administrative data was collected on all head and neck CTAs ordered within the ED at two high-volume community hospitals and an affiliated urgent care centre during the 6-year period between January 1, 2014, and December 31, 2019. Of those patients who underwent CTA, we identified those who were then transferred to a regional stroke centre for consideration of EVT and those who underwent carotid endarterectomy or stenting within 14 days.

RESULTS

A total of 4719 CTAs were ordered during the 6-year period. There was nearly a tenfold rise in the yearly number of CTAs ordered per 10,000 ED visits, from 5.3 (in 2014) to 53.1 (in 2019). A total of 164 patients who underwent CTAs (3.5%) were ultimately transferred to a regional tertiary care centre, of whom 43 (0.9%) were transferred to a regional stroke centre for consideration of EVT. A total of 61 (1.3%) patients underwent a carotid intervention within 14 days.

CONCLUSION

Little is known of the impacts on healthcare resources that have resulted from the system-wide changes made necessary by the widespread adoption of EVT. Our study shows that at our site, these system changes have resulted in large increases in CTA utilization with very small numbers of patients ultimately undergoing EVT or carotid intervention.

Multidisciplinary quality improvement initiative to optimize acute neurovascular imaging for transient ischemic attack or minor stroke

BACKGROUND

Neurovascular imaging for patients with high-risk transient ischemic attack (TIA) or minor stroke in the emergency department (ED) with computed tomography angiography (CTA) of the head and neck is the guideline-recommended standard of care, but it is underutilized in routine practice. We conducted a quality initiative to improve adherence to guidelines.

METHODS

Between January 2017 and March 2019, we implemented a decision support tool integrated into the electronic ordering system to guide ED physicians to order a CTA on patients with high-risk TIA or minor stroke defined as ongoing neurological deficits in the ED or resolved motor or speech deficits in the preceding 48 h. Data were collected retrospectively pre-intervention and prospectively post-intervention. We used an interrupted time-series analysis for the before-after comparison of the use of CTA among patients who met criteria (main process measure) and those who did not meet criteria (balancing measure).

RESULTS

Among 861 patients with TIA or minor stroke, the proportion of patients with high-risk events imaged with a CTA in the ED increased from 12.0% pre-intervention to 77.0% post-intervention and this shift was sustained over 11 months. CTA use in those without high-risk events increased to a lesser extent (15.3% versus 42.9%). The interrupted time-series analysis showed a step change immediately post-intervention where the increase in CTA use in patients with high-risk events was 51.7% higher than its use in those without high-risk events (p < 0.001). Compared to pre-intervention, the median ED length of stay increased by 2 h and neurology consultation in the ED was more frequent (5.8% versus 19.5%) post-intervention.

CONCLUSION

We provide a detailed framework that improved adherence to acute imaging guidelines for patients with TIA or minor stroke and anticipate that our approach could improve acute imaging for such patients in most EDs.

Redundant Imaging in Transient Ischemic Attack: Evidence From the Nationwide Emergency Department Sample

PURPOSE

Increasing emergency department (ED) compliance with transient ischemic attack (TIA) imaging guidelines has previously been demonstrated, along with a substantial rise in imaging utilization over the past decade. The purpose of this study was to characterize the most commonly used combinations of imaging studies during ED workup of TIA and to quantify prevalence of redundant imaging (RI).

METHODS

TIA discharges from EDs in the United States from 2006 to 2017 were identified in the Nationwide Emergency Department Sample. Brain and neurovascular imaging obtained during the encounter was identified using Current Procedural Terminology codes. RI was defined as an ED encounter with any duplicate cross-sectional brain, brain-vascular, or neck-vascular imaging. Patient demographics and hospital characteristics were incorporated into a multivariable logistic regression analysis to identify significant associations with RI.

RESULTS

There were 184,870 discharges with TIA from EDs in 2017. RI (brain) was observed in 55,513 (30%) of encounters. RI (brain-vascular) and RI (neck-vascular) imaging was identified in 5,149 (2.8%) and 1,325 (0.7%) of encounters, respectively. Decreased odds of obtaining RI was observed in Medicaid patients(odds ratio [OR: 0.72, 95% confidence interval [CI]: 0.64-0.81), non-trauma centers(OR: 0.49, 95% CI: 0.26-0.93), rural hospital locations(OR: 0.18, 95% CI: 0.11-0.29), and weekend encounters(OR: 0.9, 95% CI: 0.85-0.96). Trend analysis from 2006 to 2017 demonstrated a rise in RI (brain) from 2.3% of encounters in 2006 to 30% of encounters in 2017. RI for patients discharged from EDs with TIA in 2017 resulted in additional charges of approximately US $8,670,832.

CONCLUSION

Increased imaging utilization for TIA workup across EDs in the United States is associated with rising use of redundant imaging. We identify imaging practices that could be targeted to mitigate health care expenditures, while adhering to TIA imaging guidelines.

Diagnosis and Management of Transient Ischemic Attack and Acute Ischemic Stroke: A Review

IMPORTANCE

Stroke is the fifth leading cause of death and a leading cause of disability in the United States, affecting nearly 800 000 individuals annually.

OBSERVATIONS

Sudden neurologic dysfunction caused by focal brain ischemia with imaging evidence of acute infarction defines acute ischemic stroke (AIS), while an ischemic episode with neurologic deficits but without acute infarction defines transient ischemic attack (TIA). An estimated 7.5% to 17.4% of patients with TIA will have a stroke in the next 3 months. Patients presenting with nondisabling AIS or high-risk TIA (defined as a score ≥4 on the age, blood pressure, clinical symptoms, duration, diabetes [ABCD2] instrument; range, 0-7 [7 indicating worst stroke risk]), who do not have severe carotid stenosis or atrial fibrillation, should receive dual antiplatelet therapy with aspirin and clopidigrel within 24 hours of presentation. Subsequently, combined aspirin and clopidigrel for 3 weeks followed by single antiplatelet therapy reduces stroke risk from 7.8% to 5.2% (hazard ratio, 0.66 [95% CI, 0.56-0.77]). Patients with symptomatic carotid stenosis should receive carotid revascularization and single antiplatelet therapy, and those with atrial fibrillation should receive anticoagulation. In patients presenting with AIS and disabling deficits interfering with activities of daily living, intravenous alteplase improves the likelihood of minimal or no disability by 39% with intravenous recombinant tissue plasminogen activator (IV rtPA) vs 26% with placebo (odds ratio [OR], 1.6 [95% CI, 1.1-2.6]) when administered within 3 hours of presentation and by 35.3% with IV rtPA vs 30.1% with placebo (OR, 1.3 [95% CI, 1.1-1.5]) when administered within 3 to 4.5 hours of presentation. Patients with disabling AIS due to anterior circulation large-vessel occlusions are more likely to be functionally independent when treated with mechanical thrombectomy within 6 hours of presentation vs medical therapy alone (46.0% vs 26.5%; OR, 2.49 [95% CI, 1.76-3.53]) or when treated within 6 to 24 hours after symptom onset if they have a large ratio of ischemic to infarcted tissue on brain magnetic resonance diffusion or computed tomography perfusion imaging (modified Rankin Scale score 0-2: 53% vs 18%; OR, 4.92 [95% CI, 2.87-8.44]).

CONCLUSIONS AND RELEVANCE

Dual antiplatelet therapy initiated within 24 hours of symptom onset and continued for 3 weeks reduces stroke risk in select patients with high-risk TIA and minor stroke. For select patients with disabling AIS, thrombolysis within 4.5 hours and mechanical thrombectomy within 24 hours after symptom onset improves functional outcomes.