Patient and Hospital Rurality are Associated with Mortality in Acute Ischemic Stroke Patients with or without Inter-Hospital Transfer - A 10 Year National (Nationwide) Inpatient Sample Analysis

Introduction: In this study, we explored trends in mortality and inter-hospital transfers before and after the publication of influential mechanical thrombectomy trial results in 2015.

Methods: We selected patients with a primary diagnosis of Acute Ischemic Stroke (AIS) using ICD-9/ICD-10 codes from the 2009 - 2019 National and Nationwide Inpatient Sample (NIS) database. Patients were divided into disease course subclasses based on both transfer status and treatments (IV tPA and/or mechanical thrombectomy). Patients were stratified based on whether they were admitted pre-mechanical thrombectomy trials (2009 - 2014) or during/post-mechanical thrombectomy trials (2015 - 2019). Regression analyses were performed to identify significant factors associated with mortality in both groups.

Results: Overall, we identified an estimated weighted subpopulation of 4,485,759 patients with a qualifying Acute Ischemic Stroke diagnosis from 2009 to 2019. The percentage of transferred AIS patients rose every year starting from 3.75% in 2009 to 12.02% in 2019. Mortality rates among patients with AIS fell slightly overall (4.50% in 2009 to 3.51% in 2019) in that same time period. Among treated AIS patients, the percentage of patients transferred rose overall from 8.75% in 2009 to 19.70% in 2019. Overall mortality percentages dropped among treated AIS patients, from 10.73% in 2009 to 5.55% in 2019. Multivariate logistic regressions incorporating disease course, patient, and hospital factors showed that a rural hospital location was associated with mortality in the “pre-thrombectomy trials group” and a more rural patient location was associated with mortality in the “post-thrombectomy trials group” (p < 0.001).

Conclusion : Based on these results, factors related to both hospital and patient rurality may be significantly associated with mortality. Further analysis is required to fully characterize the effect of rurality in order to decrease mortality among these patients.