Regional Disparities in Hyperacute Treatment and Functional Outcomes after Acute Ischemic Stroke in Japan.

Abstract

This study investigated the impact of rurality on acute ischemic stroke (AIS) outcomes, emphasizing the hyperacute phase, in which immediate care is crucial. This retrospective cohort study analyzed data from a large Japanese hospital network covering AIS patients from 2013-2021, was analyzed. The focus was on patients admitted within 4.5 h of the onset, using the Rurality Index for Japan (RIJ) to categorize patients into rural or urban groups. This study examined treatment methods (intravenous thrombolysis [IVT] and mechanical thrombectomy [MT]) and functional outcomes measured using the modified Rankin Scale (mRS), where scores of 3-6 indicated poor outcomes. Multilevel logistic regression was used to calculate the adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for poor outcomes based on rurality. The study also evaluated the population-attributable fraction (PAF) to estimate potential outcome improvements in urban settings. Of 27,691 patients, 17,516 were included in the total cohort and 4,954 in the hyperacute cohort. Urban patients constituted 73.7% (12,902), with higher IVT (5.2%) and MT (3.6%) rates than rural patients (4.1% IVT, 2.0% MT). Poor mRS outcomes were more common in rural areas than in urban areas, with adjusted ORs of 1.30 (1.18-1.43) in the total cohort and 1.43 (1.19-1.70) in the hyperacute cohort. The PAF for poor outcomes due to rural residency was 14.8% (0.5%-31.0%). This study demonstrated a notable association between rurality and poorer AIS outcomes in Japan, particularly in the hyperacute phase.