2026-08-03 国立循環器病研究センター
国立循環器病研究センターの研究グループは、日本脳卒中データバンクに登録された2005～2023年の脳梗塞・脳出血患者22万8,127例を解析し、脳卒中の季節変動とその長期的変化を調査した。その結果、脳梗塞全体では季節差は非常に小さく、「夏に多い」という明確な傾向は認められず、この特徴は約19年間ほぼ変化しなかった。病型別では、心原性脳塞栓症は冬にやや多く、ラクナ梗塞は冬に少ない傾向がみられたが、いずれも差は限定的で、ラクナ梗塞では近年季節差がほぼ消失した。一方、脳出血は一貫して冬に多く夏に少ない傾向を示し、この特徴は全解析期間で維持された。また、新型コロナウイルス流行による生活様式の変化後も、季節変動に大きな変化は認められなかった。これらの結果から、脳梗塞は季節に関係なく年間を通じた危険因子管理が重要であり、脳出血については特に冬季の血圧管理に注意を払う必要があることが示された。
＜関連情報＞
- https://www.ncvc.go.jp/hospital/topics/topics_37823/
- https://www.ahajournals.org/doi/abs/10.1161/str.57.suppl_1.TP121?af=R
2005年から2023年までの日本全国レジストリにおける虚血性脳卒中および脳内出血による入院件数の季節変動の経時的傾向 Temporal Trends in Seasonal Variation of Frequency for Ischemic Stroke and Intracerebral Hemorrhage Admissions in a Nationwide Japanese Registry, 2005–2023
Tomohide Yoshie, Sohei Yoshimura, Kazunori Toyoda, Kaori Miwa, Shinichi Wada, Yoshihiro Miyamoto, Junji Miyazaki, Eiichiro Nagata, Shotai Kobayashi, Masatoshi Koga
International Stroke Conference 2026
Stroke Published: 29 January 2026
DOI:https://doi.org/10.1161/str.57.suppl_1.TP121
Abstract
Introduction: Seasonal variation in stroke incidence has often been reported, but over the past two decades, climate and behavior have changed markedly, including global warming and COVID-19–related stay-at-home orders. We evaluated temporal trends in the seasonal distribution of hospital admissions for ischemic stroke and intracerebral hemorrhage (ICH) from 2005 to 2023.
Methods: We analyzed patients in the Japan Stroke Data Bank, a multicenter prospective registry, from 2005 to 2023. We calculated seasonal proportions of admissions for ischemic stroke and ICH overall and by ischemic stroke subtype (large-artery atherosclerosis [LAA], cardioembolic [CE], and lacunar infarction). Seasons were defined as spring (March–May), summer (June–August), autumn (September–November), and winter (December–February). Seasonal distributions were summarized within four epochs (2005–2009, 2010–2014, 2015–2019, 2020–2023).
Results: Overall, 228,127 cases were included. The ICH proportion was highest in winter (22.3%) and lowest in summer (17.5%) (p<0.001). This winter-peak/summer-low pattern persisted across epochs, with odds ratios for summer vs winter ranging from 0.70 to 0.76. The winter peak in ICH strengthened after 2015, and the same tendency was observed during the COVID era (2020–2023). In contrast, seasonal variation in ischemic stroke was small. By ischemic stroke subtype, lacunar infarction was modestly lower in winter (spring–autumn vs winter odds ratios, 1.05–1.08), whereas CE was modestly higher in winter (summer–autumn vs winter odds ratios, 0.91–0.92). Over time, lacunar seasonality attenuated, with no significant differences during 2020–2023, while the CE winter peak gradually strengthened and was most evident in 2020–2023. LAA showed no significant seasonal variation across epochs.
Conclusions: Across 2005–2023, the ICH winter-peak/summer-low pattern persisted. Although overall seasonal variation in ischemic stroke was small, the winter peak of CE and winter low of lacunar persisted; CE seasonality slightly strengthened, whereas lacunar seasonality weakened over time. These directions were consistent during the COVID era, indicating that the pandemic did not introduce a fundamentally different seasonal pattern.
