Trends in Emergent Interfacility Ischemic Stroke Transfers, 2016-2022

Interfacility transfer for emergent treatment is critical to stroke systems of care. Understanding the transfer population enables transfer system optimization.

We performed a nationwide longitudinal cross-sectional study to characterize the population emergently transferred for ischemic stroke care from 2016 to 2022. Using Medicare fee-for-service (FFS) claims, we included patients 65 years or older admitted with ischemic stroke. County-level Medicare Advantage penetration rates were used to extrapolate the results to estimate nationwide emergent transfers. Multilevel logistic regression identified features distinguishing the transferred from the nontransferred population.

From 2016 to 2022, we identified 824,551 FFS beneficiaries (57% female) admitted for ischemic stroke: 99,751 (12%) underwent emergent transfer, while 724,800 (88%) were not transferred. The transfer population was younger (mean 78.2 years vs 80.1 years) with a higher rate of thrombectomy (15.9% vs 2.8%) and thrombolysis (24.1% vs 10.0%). Their presenting facility was more likely to be rural (55.3% vs 22.6%), have <100 beds (56.6% vs 11.9%), or be a critical access hospital (24.9% vs 2.8%). Nontransferred patients more frequently presented to a teaching facility (66.2% vs 32.3%), stroke center (83.2% vs 51.9%), or vertically integrated facility (93.5% vs 76.5%). Estimated nationwide emergent transfers increased from 2016 (21,221; 12% of admissions) to 2019 (26,720; 15%) and then decreased through 2022 (21,902; 12%). Multilevel logistic modeling showed a strong association between the transfer population and presentation to a critical access hospital (OR 2.8, 95% CI 2.4-3.3), prestroke hemiplegia (OR 2.3, 95% CI 2.3-2.4), or prestroke cerebrovascular disease (OR 2.2, 95% CI 2.2-2.3). Features associated with the nontransferred population include presentation to a facility with >400 beds (OR 0.01, 95% CI 0.01-0.01, reference ≤100 beds), a stroke center (OR 0.4, 95% CI 0.4-0.5), older age (OR 0.6, 95% CI 0.6-0.6), and more affluence (4th quartile of ADI OR 0.6, 95% CI 0.5-0.7).

Emergent transfers for ischemic stroke in the United States have decreased since 2019, reversing a long-standing trend of continual increase. Receipt of thrombectomy or thrombolysis, presentation to a small facility, a nonstroke center, or in a less affluent area are associated with the transfer population.