Cumulative Incidence of Stroke Disability and Mortality Following Emergency Department Discharge for Dizziness: A Cohort Study

Comprehensive Summary

This article investigates the risk of stroke, disability, and mortality after patients are discharged home from the emergency department with dizziness, which is a common presentation that can occasionally represent a missed stroke. Using a large retrospective cohort from Kaiser Permanente Southern California (13 medical centers) between 2016 and 2020, the authors analyzed 77,315 adult dizziness visits discharged home, tracking 30 day stroke hospitalizations and stroke related disability or death using the Kaplan Maier estimates. Strokes type, imaging findings, acute interventions, and modified Rankin Scale (mRS) outcomes were also collected to contextualize severity. The 30 day cumulative incidence of any stroke hospitalization was at 0.12 % (94 events, 1 in around 830, 95 % CI 0.10 - 0.15), while the incidence of stroke with disability or mortality was 0.04 % (33 events, 1 in around 2,500, 95 % CI 0.03 -0.06). Among the subsequent strokes, 78 % were ischemic, 14 % intracerebral hemorrhage (ICH), and 9 % subarachnoid hemorrhage. Imaging showed that 55 % of infarcts were in the anterior fossa (52/94) and only 40 % in the posterior fossa, which is the region that is typically associated with dizziness stroke. Acute stroke interventions were rare. This included 1 % thrombolysis, 5 % thrombectomy, 2 % craniectomy, and 10 % mechanical ventilation, suggesting that most strokes were not catastrophic. Overall functional outcomes reflected mild to moderate severity, with a median mRS of 2.5 (IQR 0 - 4), and 53 % of patients able to walk unassisted at discharge. Sensitivity analyses, restricting to primary dizziness diagnoses or adding National Death Index deaths, produced nearly identical incidence estimates, strengthening the robustness of these findings.

Outcomes and Implications

These findings are important because ED dizziness is one of the most anxiety provoking presentations for clinicians who fear missing a posterior circulation stroke, a diagnosis that can carry high mortality if it is overlooked. However, the study shows that severe or fatal missed strokes are exceedingly rare. It is only in around 2500 dizziness discharges leading to a stroke hospitalization with disability or death within 30 days. The reassuring fact is that many of these likely have no kind of causal link to the initial dizziness visit. Only 40 % were posterior circulation lesions and ischemic stroke accounts for 78 %, which is far below the ≥ 90 % typically expected for dizziness stroke presentations. This strongly shows that the true rate of clinically meaningful missed strokes is even lower that the already small cumulative incidence suggests. Clinically, these data support a more measured approach to stroke evaluation in ED dizziness visits. Due to the rate being low, even a highly accurate diagnostic tool with 98 % sensitivity and 99 % specificity would produce 25 false positives for every true positive and 250 to 1 if specificity is lowered to 90 %. So, the widespread imaging or aggressive screening would likely overburden systems without improving patient outcomes in any way. Instead, the findings favor focusing diagnostic attention on clearly higher risk groups. Those are the ones with new symptoms, vascular risk factors, nystagmus, imbalance, or any sort of inability to identify a benign peripheral cause. Implementing interventions to reduce missed strokes that are dizziness related would require > 200,000 index visits to show meaningful benefit due to event rarity. Overall, this reassures clinicians that the vast majority of ED dizziness patients can be safely discharged, and the in the future pragmatic vascular risk reduction rather than universal high-intensity stroke screening.