Access to mechanical thrombectomy and ischemic stroke mortality in Japan: a spatial ecological study

Kazuki Ohashi; Toshiya Osanai; Kensuke Fujiwara; Takumi Tanikawa; Yuji Tani; Soichiro Takamiya; Hirotaka Sato; Yasuhiro Morii; Katsuhiko Ogasawara

doi:10.3389/fneur.2023.1209446

Access to mechanical thrombectomy and ischemic stroke mortality in Japan: a spatial ecological study

Front Neurol. 2023 Sep 5:14:1209446. doi: 10.3389/fneur.2023.1209446. eCollection 2023.

Authors

Kazuki Ohashi¹, Toshiya Osanai², Kensuke Fujiwara^{1

3}, Takumi Tanikawa^{1

4}, Yuji Tani^{1

5}, Soichiro Takamiya^{2

6}, Hirotaka Sato⁷, Yasuhiro Morii^{1

8}, Katsuhiko Ogasawara¹

Affiliations

¹ Faculty of Health Sciences, Hokkaido University, Sapporo, Japan.
² Department of Neurosurgery, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan.
³ Graduate School of Commerce, Otaru University of Commerce, Otaru, Japan.
⁴ Faculty of Health Sciences, Hokkaido University of Science, Sapporo, Japan.
⁵ Department of Medical Informatics and Hospital Management, Asahikawa Medical University, Asahikawa, Japan.
⁶ Department of Neurosurgery, Otaru General Hospital, Otaru, Japan.
⁷ Department of Neurosurgery, Asahikawa Medical University, Asahikawa, Japan.
⁸ Center for Outcomes Research and Economic Evaluation for Health, National Institute of Public Health, Wako, Japan.

Abstract

Background: Advances in stroke treatment have greatly improved outcomes; however, disparities in access to treatment might increase. Achieving equitable access to stroke treatment is a health policy challenge, as rapid treatment is essential for positive outcomes. This ecological cross-sectional study aimed to determine the relationship between the disparities in spatial accessibility to mechanical thrombectomy (SAMT) and stroke mortality rates in Japan, hypothesizing that disparities in SAMT may increase the differences in stroke mortality between regions.

Methods: We used the average number of ischemic stroke (IS) deaths between 2020 and 2021 as the response variable; and SAMT, medical resources, and socioeconomic characteristics of each municipality as explanatory variables. A conditional autoregressive model was used to examine the association between the risk of stroke mortality and SAMT. The standardized mortality ratio (SMR) was mapped to understand the nationwide disparities in stroke mortality risk.

Results: The median number of IS deaths was 17.5 persons per year in the municipalities (2020 to 2021). The study also found that municipalities with low SAMT were located in the northern part of Japan. The non-spatial regression model results indicated that poor accessibility, a small proportion of bachelor's degrees or higher, and a high proportion of workers in secondary industries were related to high IS mortality. Three models were evaluated using spatial analysis; Model 1 with accessibility indicators alone, Model 2 with medical resources added to Model 1, and Model 3 with socioeconomic characteristics added to Model 2. In Models 1 and 2, the population-weighted spatial accessibility index (PWSAI) showed a significant negative relationship with stroke mortality. However, this was not evident in Model 3. Mapping using Model 3 showed that the high-risk areas were predominantly located in northern Japan, excluding Hokkaido.

Conclusion: Access to mechanical thrombectomy was estimated, and regional differences were observed. The relationship between accessibility and IS mortality is unknown; however, regardless of accessibility, municipalities with a high proportion of workers in secondary industries and a small proportion with bachelor's degrees or above are at risk of death from stroke.

Keywords: 2-step floating catchment area method; conditional autoregressive model; ischemic stroke; mechanical thrombectomy; spatial accessibility.