Highlight
- Emergent interfacility transfers for ischemic stroke rose from 12% to 15% of admissions between 2016 and 2019, then declined back to 12% by 2022.
- Transferred patients were younger, more likely to receive thrombectomy or thrombolysis, and typically originated from smaller, rural, or critical access hospitals.
- Nontransferred patients frequently presented to larger, teaching, stroke-certified, or vertically integrated hospitals and were older and from more affluent areas.
- Critical access hospital location and certain stroke-related comorbidities strongly predicted transfer likelihood, highlighting ongoing system and geographic disparities.
Study Background
Interfacility transfer is a vital component of modern ischemic stroke care systems, enabling rapid access to specialized interventions such as intravenous thrombolysis and mechanical thrombectomy. Timely transfer can significantly influence outcomes by facilitating definitive treatment that might not be available at the initial presenting hospital. Understanding patterns and determinants of emergent stroke transfers can inform stroke system design, resource allocation, and policy aimed at optimizing equitable access to advanced care. Previous decades saw consistent growth in emergent stroke transfers reflecting expanding thrombectomy indications and evolving care pathways; however, recent trends have not been fully elucidated on a national scale.
Study Design
This longitudinal cross-sectional study assessed a nationwide population of Medicare fee-for-service beneficiaries aged 65 years or older admitted for ischemic stroke from 2016 through 2022. Using administrative claims data, the study identified emergent interfacility transfers and characterized demographic, clinical, and hospital-level factors distinguishing transferred from nontransferred cohorts. To extrapolate findings to the entire U.S. population, county-level Medicare Advantage penetration was factored. Multilevel logistic regression was employed to analyze associations between patient and hospital features and transfer status, controlling for potential confounders.
Key Findings and Results
A total of 824,551 ischemic stroke admissions were analyzed, with 12% (99,751) experiencing emergent interfacility transfer. From 2016 to 2019, emergent transfers rose from 21,221 (12%) to 26,720 (15%), but then declined to 21,902 (12%) by 2022, indicating a reversal of the previous upward trajectory.
The transferred population was characterized by younger age (mean 78.2 vs. 80.1 years) and substantially higher utilization of advanced reperfusion therapies: 15.9% underwent thrombectomy and 24.1% thrombolysis versus 2.8% and 10.0% in the nontransferred group, respectively. This underscores transfer as a pathway to accessing specialized stroke treatments.
Hospital features differed markedly: transferred patients more often initially presented to rural facilities (55.3% vs. 22.6%), smaller hospitals with fewer than 100 beds (56.6% vs. 11.9%), and critical access hospitals (24.9% vs. 2.8%). Conversely, nontransferred patients predominantly presented to teaching facilities (66.2% vs. 32.3%), designated stroke centers (83.2% vs. 51.9%), and vertically integrated healthcare organizations (93.5% vs. 76.5%), suggesting better in-house capabilities resulted in less frequent need for transfer.
Regression modeling highlighted key predictors of transfer: presentation to a critical access hospital (odds ratio [OR] 2.8, 95% confidence interval [CI] 2.4-3.3), presence of prestroke hemiplegia (OR 2.3, 95% CI 2.3-2.4), and prestroke cerebrovascular disease (OR 2.2, 95% CI 2.2-2.3). Factors associated with lower likelihood of transfer included admission to hospitals with >400 beds (OR 0.01, 95% CI 0.01-0.01), stroke center status (OR 0.4, 95% CI 0.4-0.5), older age (OR 0.6, 95% CI 0.6-0.6), and higher socioeconomic status (measured by the 4th quartile of Area Deprivation Index; OR 0.6, 95% CI 0.5-0.7).
Expert Commentary
This comprehensive national analysis offers important insights into ischemic stroke care pathways. The identification of a plateau and subsequent decline in emergent transfers after 2019 may relate to maturation of regional stroke systems, improved initial hospital capabilities, or pandemic-related healthcare disruptions. The strong link between critical access hospital presentation and transfer emphasizes ongoing rural-urban disparities in stroke care access. Additionally, younger patients receiving higher rates of thrombectomy reflect current guidelines favoring intervention in selected patients with favorable functional status and imaging profiles.
From a policy perspective, these trends highlight areas for targeted improvement, including bolstering stroke care capacities at smaller or rural hospitals through telemedicine and resource allocation, and addressing socioeconomic barriers that may influence transfer decisions. It is also essential to consider that nontransferred patients include a large proportion presenting directly to comprehensive stroke centers, thus underscoring that emergent transfer remains a central feature primarily for patients initially evaluated in resource-limited settings.
Limitations include the reliance on administrative claims, which may misclassify some clinical variables or transfers, and the focus on the Medicare fee-for-service population, which may not fully capture younger or Medicare Advantage beneficiaries. Nevertheless, the study’s use of multilevel models and national extrapolation strengthens the validity of findings.
Conclusion
Emergent interfacility transfers for ischemic stroke in the United States exhibited an initial increase followed by a decline post-2019, reversing a previous trend of continual growth. Transfer status closely correlates with hospital size and capabilities, rural location, and patient comorbidity profiles. These findings underscore the critical role of transfer systems in bridging gaps for advanced stroke care and the necessity of ongoing efforts to optimize stroke systems, particularly in rural and resource-constrained settings. Future research should investigate the impact of these trends on patient outcomes and explore strategies to further enhance equitable access to advanced ischemic stroke therapies nationwide.
Funding and ClinicalTrials.gov
The study was supported by institutional research funds. No clinical trial registration was applicable as this was an observational claims-based study.
References
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- Mullen M, Prabhakaran S. Telemedicine in Stroke Care: An Evidence-Based Review. Neurol Clin. 2021;39(2):399-412.
