Potential crowdedness of mechanical thrombectomy and cerebral infarction mortality in Japan: Application of inverted two-step floating catchment area method.

OBJECTIVES: This study aimed to evaluate a stroke medical delivery system based on population coverage and the potential crowdedness index (PCI) of mechanical thrombectomy and investigate the relationship between PCI and cerebral infarction mortality in Japan. MATERIALS AND METHODS: This cross-sectional study defined 662 facilities and 1605 neurointerventionalists as supply, population aged 55 years or older as demand, and set the reachable area for demand as 120 min in driving time. Multiple regression analysis adjusted for spatial autocorrelation was used to examine the relationship between PCI and cerebral infarction mortality. RESULTS: In the 2020 data, 99% of the population aged 55 years or older had access to mechanical thrombectomy (≤120 min), and the PCI ranged from 5876 to 129838, with a median of 30426. From 2020 to 2035, the PCI is estimated to increase (30426 to 32510), decreasing after 2035 (32510 to 29469). The PCI distribution exhibited geographical heterogeneity. High PCI values emerged in eastern Japan. According to regression analysis, the increase in PCI by 1% led to an increase of 0.13% in standardized mortality ratio of cerebral infarction in men. However, PCI did not significantly correlate with cerebral infarction mortality in women. CONCLUSIONS: PCI for hospitals based on supply and demand was geographically heterogeneous in Japan. Optimization of PCI contributes equalization of mechanical thrombectomy provision system and may improve cerebral infarction mortality.

Analyzing Cost-Effectiveness of Allocating Neurointerventionist for Drive and Retrieve System for Patients with Acute Ischemic Stroke.

OBJECTIVES: There are regional disparities in implementation rates of endovascular thrombectomy due to time and resource constraints such as endovascular thrombectomy specialists. In Hokkaido, Japan, Drive and Retrieve System (DRS), where endovascular thrombectomy specialists perform early endovascular thrombectomies by traveling from the facilities where they normally work to facilities closer to the patient. This study analyzed the cost-effectiveness of allocating a endovascular thrombectomy specialist for DRS to treat stroke patients. MATERIALS AND METHODS: he number of ischemic stroke patients expected to receive endovascular thrombectomy in Hokkaido in 2015 was estimated. It was assumed that an additional neutointerventionist was allocated for DRS. The analysis was performed from the government's perspective, which includes medical and nursing-care costs, and the personnel cost for endovascular thrombectomy specialist. The analysis was conducted comparing the current scenario, where patients received endovascular thrombectomy in facilities where endovascular thrombectomy specialists normally work, with the scenario with DRS within 60 min drive distance. Patient transport time was analyzed using geographic information system, and patient severity was estimated from the transport time. The primary outcome was incremental cost-effectiveness ratio (ICER) in each medical area which was calculated from the incremental costs and the incremental quality-adjusted life years (QALYs), estimated from patient severity using published literature. The entire process was repeated 100 times. RESULTS: DRS was most cost-effective in Kamikawachubu area, where the ICER was $14,173±16,802/QALY, significantly lower than the threshold that the Japanese guideline suggested. CONCLUSIONS: Since DRS was cost-effective in Kamikawachubu area, the area should be prioritized when a endovascular thrombectomy specialist for DRS is allocated as a policy.