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

Multisociety guidelines recommend urgent brain and neurovascular imaging in patients with transient ischemic attack (TIA) to identify and treat modifiable stroke risk factors. Prior research suggests that most patients with TIA presenting to the emergency department (ED) do not receive prompt neurovascular imaging. The purpose of this study was to evaluate the association between incomplete neurovascular imaging workup during ED encounters for TIA and odds of subsequent stroke. 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-10 and CPT codes. Patients 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 undergoing 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. The sample included 111,417 patients (47,370 men, 64,047 women; 26.0% with age >84 years) with TIA ED encounters. A total of 37.3% (41,592) of patients 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 1.3 [95% CI: 1.23-1.38]) when adjusting for patient (age, sex, race and ethnicity, high-risk comorbidities, median county household income) and hospital (region, rurality, number of beds, major teaching hospital designation) characteristics. TIA ED encounters with incomplete neurovascular imaging were associated with higher odds of subsequent stroke within 90 days. Increased access to urgent neurovascular imaging in patients with TIA may represent a target that could facilitate detection and treatment of modifiable stroke risk factors.