Regional Disparity of Reperfusion Therapy for Acute Ischemic Stroke in Japan: A Retrospective Analysis of Nationwide Claims Data from 2010 to 2015

BACKGROUND: We aimed to determine whether a regional disparity exists in usage of reperfusion therapy (intravenous recombinant tissue plasminogen activator [IV rt‐PA] and endovascular thrombectomy [EVT]) and post‐reperfusion 30‐day mortality in patients with acute ischemic stroke, and which regional factors are associated with their usage. METHODS AND RESULTS: We retrospectively investigated 69 948 patients (mean age±SD, 74.9±12.0 years; women, 41.4%) with acute ischemic stroke treated with reperfusion therapy between April 2010 and March 2016 in Japan using nationwide claims data. Regional disparity was evaluated using Gini coefficients for age‐ and sex‐adjusted usage of reperfusion therapy and 30‐day post‐reperfusion in‐hospital death ratio in 47 administrative regions. The association between regional factors and reperfusion therapy usage was evaluated with fixed‐effects regression models. During the study period, Gini coefficients showed low inequality (0.11–0.15) for use of IV rt‐PA monotherapy and IV rt‐PA and/or EVT and extreme inequality (0.49) for EVT usage in 2010, which became moderate inequality (0.25) by 2015. The densities of stroke centers and endovascular specialists, as well as market concentration, were associated with increased usage of reperfusion therapy whereas the proportion of rural residents and delayed ambulance transport were negatively associated with usage. Inequality in the standardized death ratio after EVT was extreme (0.86) in 2010 but became moderate (0.29) by 2015; inequality was low to moderate (0.17–0.23) for IV rt‐PA monotherapy and IV rt‐PA and/or EVT. CONCLUSIONS: Scrutinizing existing data sources revealed regional disparity in reperfusion therapy for acute ischemic stroke and its associated regional factors in Japan.